Memory... How much memory does your computer have? You may not have enough memory. I was building a complex level with just 256 MB memory, so I'm theorizing that you have 128 MB. Also, try running a virus scan or spyware scan as they might be a problem. Also, disconnect from the internet, as something might be downloading without you knowing. These are some suggestions. I haven't read through this thread entirely, but the 7 or so latest posts between you and JCL.

"You level up the fastest and easiest if you do things at your own level and no higher or lower" - useful tip My 2D game - release on Jun 13th; My tutorials