Don't tell me your getting the same error message? Can you restart your PC after installing?
The message your receiving (regardless of running iTunes) is a quicktime message. iTunes is only a player for the codec's (Quicktime being one of them) that actually displays .qt movie files on your PC.
Take a look also at the Quicktime website regarding this, aparently well known problem with good old Quicktime:
Error -2096 message when opening QuickTime for Windows in Compatibility Mode (Make sure QT isn't running in compatibility mode).