I've been working with an installation of QuickBooks 2008 this evening. Everything on the machine appears to be working properly and QuickBooks tries to start, but fails.

In doing some research, it appears that .NET on the machine got screwed up somehow. I think that uninstalling .NET (1 & 2) and reinstalling might fix the problem.

.NET 2 (for sure) isn't uninstalling from Add & Remove programs, so I'll have to do it manually (way to go Microsoft).

At work, we do use Quickbooks for payroll (smallish company, so it works well - older versions have been ok to support and it is way better than the previous payroll package that we were using) and are being forced to upgrade this year. Not something I am looking forward to.