when i try to reply to some topics it says "sorry you do not have permission to reply to that topic". why is this?

I presume that you are talking about replying to Hijackthis logs.
The forum enforces a rule that only allows HJT team members to reply to these threads.
This firstly saves confusion, and also removes the possibility of faulty instructions by normal members.
If you are looking for more topics to post your solution to SpyDawn, please stop.
You have already posted about the same thing twice, please do not post about it again.

If you would like to learn about how to help with Hijackthis logs, I recommend you read here:
http://www.geekstogo.com/forum/Would_you_l...ware-t4817.html

Some topics, primarily those that are pinned and are informational in nature, are closed and replying to these is prevented. If you have questions or comments about these pinned topics, you may post either in one of the general forums, or in the forum where the topic resides.
Please provide an example of a post to which you cannot reply.
Regards,
John