Thanks very much SP, but I'm afraid it doesn't seem to work. The strange thing is, it is stable while working on a new track, the problem only seems to appear when the programme is closed down and then re-opened. I've been using Acid for quite a few years and have never come across this issue before.

@Jeremy-Phillips Does that happen with each project or only if you use Kontakt or EZ Drummer?

@Jeremy-Phillips Does that happen with each project or only if you use Kontakt or EZ Drummer?

When I use kontakt and ezdrummer. But I've been using them for years with no issues

@Jeremy-Phillips If it suddenly doesn't work any longer and a program reset doesn't help, it might be caused by a Windows update or a Kontakt/EZ Drummer update. Did you install something over the last couple of days?

Nothing installed by me, though there was a windows update IIRC.

@Jeremy-Phillips Jeremy, is it Kontakt 7 and EZD 3....?

K7 & EZD3 don't work well (or at all) in AP. This is another of the known issue in AP, Cheers

K6 and EZD 2. Does Superior Drummer 3 work ok?

Hey Jeremy. I've been using ACID since it's first release back in 1997. Acid has ALWAYS been buggy and unstable (don't get me wrong, I have produced and released several records that were made with Acid, but most definitely not without their headaches). While Acid as truly come a LONG way, sadly, the best people who understood the product the most were the original owners, Sonic Foundry. The product has gone through so many different releases, each with either new or great problems. And some good things, too. The implementation of MIDI was nightmare until version 6 (Sony's turn at it). MIDI suddenly became a viable option to utilize the new soft synths that were coming out (that all my studio producer friends laughed their asses off at me when I tried to convince them that this Acid thing was going to work, eventually. I wonder where they are now with their AKAI 2300 SCSI samplers and knowledge of an entirely useless production model. But I digress. You are using a relatively old version of Acid (8). While I can't recall it's good or bad things, I do remember that the most significant change to the update was the inclusion of the green Sony splashscreen at the intro (sad that's all I remember about it).

Sony had it's fair share of successes with the product, although seeing their investment through to creating the stable product they envisioned and promised clearly didn't happen. Acid is a revolutionary approach to music making and I can only imagine the complicated mess of code to get it all to work, but it usually does. Until you start brushing up against ANY of the physical hardware limits of your computer. Acid is a dictator who likes, no demands every available resource your computer can give it or it will make your work pay the price. Yes, it always gives you that faint glimmer of hope when you restart and asks you if you want to recover your previous session. The number of times I sat there, chewing my fingernails, clenched fists waiting for that recoverry effort to conclude, only to find out that the recovery it found was actually my last save. Conveniently five hours full of work that transpired before the crash. The number of projects I have thrown away because of Acid's failures are far too many to even think about without getting furious and swearing off it again.

BUT, here we are anyway and you're having what I assume is a MIDI-type of error. As you may have noticed there are certain software companies that even though they are perfectly able to make their products play nice with everybody else's, have ulterior motives and sales depts of their own to answer to and *poof* there's a bug "somewhere" that nobody seems to be able to work out. I'm sort of betting that MAGIX coders can see Acid's code in their brains when they are asleep, so it's probably not an Acid thing, unless it stems from too few resources. That could be solved by banging out your midi in as final a form as you can and then "freezing" the midi. What that does (in case you don't know) is relieve Acid from having to control the MIDI component and turns your data MIDI stream into an audio file, which is what ACID likes to do best. Of course if you need to change the track, you'll have to unfreeze it and MIDI-ize and then refreeze the track. See if that helps with what you've already got running before trying to change the tone generating component.. And I know this is probably a stupid suggestion, but what the Hell. When you start Acid, make sure there's nothing else competing for your computer's affection like internet, leaving browsers open, or any apps at all, actually. I've found that when Acid is at her buggy worst, I will yank the internet connection off the machine entirely until Acid straightens itself out and flies correct.

Obviously I know nothing of your financial resources, but if computer upgrades are on your horizon, go as big and busty as you can afford (by busty I mean do doubleD Rams ... as much as you can and an SSD will help significantly) You might want to upgrade Acid as well, but maybe not. Understandably. I have the ultimate love/hate relationship with Acid. I love it for it's total and utterly simple concept. Paint with sound. I hate it because the second you try and get it to do what it so boldly boasts it can do, it can't. by the time you get a couple of effects going, try to run a synth or two and your nightmare begins. At the first signs of trouble, I create a new Acid file and copy all my work over to the new file, then reload things one at a time like effects and midi to see if I can eliminate a problem that way. If the same things inevitably start happening again, it's time for me to give up the concept happening with the Acid world, because it won't There is now either some little tine corrupt bit in the code, or one of the files i'm using is irretrievably corrupt. I also find that NOT working with MP3 clips helps, A LOT. If you have any, try converting them into WAV files. MP3 like to act like the little dodgy once-illegal things that they are. Indicated by symptoms like your inability to put the cursor precisely where you want to, or to get rid of that short space at the beginning of the file because you can't. That's an MP3 coding thing that won't ever go away (unless you save the file as a WAV or if you're Mac, I'm sorry. then you will have to convert it to an AIFF file (am i the only one who finds it SO annoying that iTunes REFUSES to acknoweldge FLAC and makes me go through the efffort of converting what is already a pristine file and changing it to theirs? Not a big mac fan here, but i digress).

Dang that's a lot of text. Sorry about that dude. I hope something in there helps. Let me know if there's anything else we can try and troubleshoot. Good Luck!

Thanks very much for your extensive reply. Some excellent suggestions which I will definitely try, especially freezing the midi tracks. I've been using Acid for about ten years and when it works, it suits me down to the ground. It's only a midi issue as I never have this problem with audio. I really don't want to go through the annoyance of learning a new daw as fluently as I can use Acid. Thanks again for your help, and I'll let you know how it goes.

@Jeremy-Phillips EZD3 won't work in AP. Do NOT upgrade to any version of AP. They are all unstable and bug ridden. AP10 (8&9 as well) will not be patched or updated, it is 'tot'. VST3 & VSTi3 are a guaranty of problems in AP & Vegas. One last thing, DannyNYC's advice about working with MP3s is spot on. MP3's are for consumers as an end product. Production and masters should be done in Wave or AIFF on a Mac. Best of luck & Cheers