Problems! user accounts/windows sidebar/McAfee

Hi,

Have bought new computer with Vista Home Premium (x32) was working relatively fine but am now having the following problems which all started the same day. I have the administrator account and there are three other user accounts.

#1 Windows sidebar gadgets stopped working, just blank boxes etc. They're working again on my account but not the others.

#2 McAfee security centre wouldn't open on any account, just a blank window opened, I couldn't run scans or do anything even though the icon showed as still protecting the computer. Thankfully it started working again on my user account but yet again the other users still get a blank page. We could access security centre on the other users prior to this problem. I did contact McAfee (after running the virtual technician and scans with no problems being found) They got me to run the McAfee cleanup tool and to reinstall the security suite saying it would fix my problems but unfortunately this didn't change anything.

#3 The other users can't get past log in pages on websites (eg hotmail, myspace or any site requiring log in at some point) Yet again this was a problem on my account also but fixed itself. Naturally not being able to access sites fully is very frustrating for the other users and also means I have to let them use my account to check things. All sites are on the allowed list and were working fine before this started.

The problems on my account fixed themselves gradually a day or two after starting. I've been unable to find help elsewhere so am hoping someone has some advice!

Thanks for your time.