Corel crashing due to X5 or Computer?

I am working in CorelDRAWX5 with some very large PSD and TIFF files, some over 50mb each, Corel has locked up and crashed numerous times.  I'm afraid this will cause me to lose the work.

Would this be due to CorelX5 or my computer system most likely?

I have a Dell AMD Athlon II X2 240 Processor 2.80 GHz

4.00 GB RAM

Windows 7

I am just wandering if I need to upgrade my computer or software to limit it locking up and crashing.