In addition to the previous suggestions (I will NOT go on reinstalling Windows...)
when projects get bigger and bigger, use many external libraries and a lot of memory,
VB tends to loose its focus :) especially if you press the Stop button in the debugger (that kills the app without closing any allocates resources.) Let's not forget that
VB is a Windows application like any others.
Save and restart
VB often.
Open the vbp file in notepead and check if all references are correct.
Marco