Much more detail required please to check the server's instability.
Check your apache\logs\error.log file for any clues.
Check your apache\logs\access.log file for any strange post or get entries at about the time you notice server issues.
Are you serving to the open Internet?
Which browser are you using?
Clear out all your browser's memory cache (temporary Internet files) as in this post by Blakeman:http://www.google.com/support/forum/p/C ... 0ff4&hl=en
Could be an issue with Firefox or Chrome browser - Google for ap_index and check out the results that relate to ap_index issues and there were a few:Chrome Redirecting Address
So perhaps this may not be an XAMPP server issue as all indications are it relates to a corrupted browser cache.
You have to be a bit of a sleuth to hunt for clues about these "weird or what" issue.