Be Secure,
please do not try to help people if you have no clue on how things are working.
Leave the help to people who have the knowledge.
cagross,
a system becoming slow can be caused by software (most of the times) but also by hardware.
Besides broken/dying hardware a bad connection and dust are common causes.
If you want, follow the instructions in the "viruses and worms" forum and someone will have a look at the log files.
I'm not saying it is malware, but it can be.
Besides that, the logs will show a lot more information than just malware issues.
They can help to solve the problem.