Hi Denis, I am new to SF and VS, but will try to give you something to think about this problem.
Are you saying that after you installed SF you can not open VS2005?
- What OS are you running?
- Did you get any error from SF installation?
- Have you tried uninstalling SF? or VS2005?
SF adds some AddIns to VS that are configured to run at VS Startup and if you had any problem with SF installation that prevented installation or corrupted the AddIn, I think that may cause this kind of symptom.
See if there is a way to make VS start without loading those AddIns.