old PC? what op system windows 7? how much RAM?
how much virtual memory
Pagefile (Virtual Memory) -- Right click MY Computer - select properties - Advanced tab - Performance - advanced tab - Virtual memory click change, you can put the page file on a different drive (if you have one), click custom size and set Initial size to one and a half times the amount of memory you have fitted i.e. 2GB memory = set to 3GB, set maximum to double your memory amount i.e. 2GB RAM = 4GB pagefile size click ok. If your hard drive is full and there is not enough room for the pagefile this can slow down, freeze or even cause the PC to crash (restart).