Make the account an admin one. Log in, run itunes and then exit. Flip it back to limited and retest.
http://discussions.apple.com/thread.jspa?threadID=1719425 and discussions there show it's a real problem. Sorry but as there must be 27 other solutions and 15 causes my idea is just one of the 42 known issues.
Am running iTunes 9 with Windows XP Home Edition; there is an administrator account (mine) and three limited user accounts. Each time the limited users logon, they must accept the EULA and any preferences they set are lost. Everything else works fine, but this is getting to be a real annoyance. It was not always this way, but started a version or so back with iTunes. Tried modifying the registry to give the limited accounts full permission, but that did not seem to help. Any suggestions?