Itunes isn't updating & I can't access the Itunes Store

Hello everyone,

I got a notification on my desktop (windows 7-HP) saying to update Itunes, Safari & Quick Player. I tried to update Itunes but it said an error has occured so I canceled it. I then clicked the Itunes shortcut but it didn't open for awhile. Once it opened, I was able to play music, but when I went to the store it said Internet Explorer has stopped working & it shut down. About a month ago I brought my computer to Best Buy to get fixed for possible viruses & Itunes hasen't been the same since. Could anything Best Buy did cause a problem? Is there anything I can do to fix it?