cd-rom/harddrive problems

I just got this computer a few weeks ago and I was having problems installing cds from my cd-rom with constant .cab errors. I was told to change the drive mode from DMA to IPO only so I did and it worked. Later that week I noticed problems on the hard drive with installing programs that had .cab files and so I changed the HDD to IPO mode too but it runs much slower and when I'm installing something, it drags. This system is 2.0 ghz AMD, 512 ddr ram, I don't believe it should be running like this. Is there any other destination I could take rather than switching my hard drive and cd-rom to IPO mode for them not to get .cab errors when installing software?

 

Try repairing the operating system but since you do not mention which one your are using it is difficult to give advice.

A computer with the specs you give should be flying.