Well, I use Windows 7 on my Dell laptop and an M-Audio fast track mixer to my microphone. It has been working fine for the past 6 months. No erros generated.
Does it do it for every new project or just the project you are working on?
Has there been any updates since you last remember it working and now?
Laptops do not actually have sound cards, they use integrated sound processors that sometimes have various drawbacks... even though you stated it has worked before it might be a taxing issue with the device. I am assuming you have Samplitude Producer 11.5 (is that correct?)
Is the correct recording device selected for the track you are wanting to record?