I use Opera 7.23 on two different machines (one Win 98 the other Win XP) and don't have that problem on either of them.
This probably isn't the cause, but have you checked that Opera's auto reload feature hasn't become enabled? It's under Navigation > Reload Every > Enabled. If you've got more than one window open be sure to check in the window which is doing the constant reloads because this setting can vary per window.
Other things to try:
Clear your cache, exit the browser, wait 30 seconds then reopen Opera and try again.
Set Opera to refuse popups, and disable plugins, Java, and Javascript.
Beyond that, you might check
this thread at the Opera support forums for some other suggestions.