It shouldn't - I'm pretty sure that "Mark forum read" will update your read stats with the current time WHEN you click on the link. Perhaps you need to refresh your cache next time you visit the forum?
Next time you're in a forum, check the clock on the upper right - if it's not your current time (assuming you've properly set your time zone), refresh the page and see if things look a bit different.
If you keep having problems, send me a private message or email.
CRZ: I've noticed that you have started clarifying your reasons for banning certain threads. Mostly the people that have threads banned don't understand and probably never would without some blatant explanation. Maybe this will increase their wisdom......