Keep getting logged out of forums

I have been having this problem for a while now. when ever i go to a phpBB platform forum I keep getting logged out when I try to look at posted jpegs.
I can look at text on the forum all day but as soon as I go to a thread with pictures I'm out. I can go to any other forum platform & have no problems.

I don't know if this is related to the problem, but when I go to some comic websites I have the opportunity to vote for my favorite strip. When trying to vote I sometimes get the message " your ip address was not the same as when you started ", & it will not let me vote.

I'm running IE 8 with AVG a/v. Wildblue is my satellite internet connection. I have tried to get info from phpBB but their info site has no troubleshooting & no way to ask a question with out being an admin. I also did a factory reboot with the same problem returning


Thanks, John