Laptop running slow and keeps freezing

Ive done a disk clean, de frag, registry clean and Malware bytes. All issues found were cleaned but its still running slow and freezing. Its usually when i try to do to many things. Im having to open 1 page at a time.

Sometimes i get a message saying "high memory usage, close and re open applications" or something along those lines. But Ive hardly got anything open when this happens.

I tried system restore but after my laptop reboots i get a message saying that it has failed to restore.

Im not sure what else to do.


Laptop details

Windows Vista centrino duo 2GB. 1.80 GHZ