The default setting for the forums is that you recieve an e-mail to say there has been a reply to a post of yours with a link to the post. This way anyone can see the thread and it may well help others. You can change your settings in user CP ..but it's not a good idea imo
I'm a bit puzzled about your problem .. so Lets try and find out what you have there
If you click on the Apple ..> about this mac you will see a panel with version, processor, and memory. Please tell us what these say.
Also click on finder in the dock and tell us what drive space you have left spare this will be at the bottom of the window in the middle ... If you have other drives listed at the top left under network in the finder window.. click on those and tell us what space is on those.
This might not help .. but it'll give us an idea what you have