1st. Separate the ide hard disk from the CD-ROM, make ide hard disk on IDE1 primary master, CD-ROM on IDE2 as secondary master. IDE are designed to share the band width. DO NOT connect ur hdd and cdrom on a same cable.

2nd, Also check the IDE cable, make sure it’s the fast cable (40pin, support UDMA100-133).

3rd, Check the power, how many watts does it provide? What is ur graphic card?

4th, Check virus.