I have recently updated my windows vista and now my pages are not refreshing properly. When I see a wikipedia page it may or may not reflect recent editorial improvements. Even if I hit the F5 button, it does not refresh to the latest text.
You can try several things...
Delete all temporary files and clear your browsing history.
Use Shift + F5 to force a refresh
Check your setting in Internet Options | Temporary Files Settings. Mine is set to Automatic and seems to work OK but I am using IE 7 and XP Pro. There are optiosn to refresh on every visit or every start of Internet Explorer.