Some serious problems with IDE bus

I have a PIII 933 based PC with ASUS CUSL2-C mainboard. Currently I have three devices attached to IDE Bus: 1) Hard disk Maxtor 6Y120P0 (120Gb UATA-133) - Pri. Master 2) Ricoh RW9200A (Combo drive DVD-ROM/CD-RW) - Sec. Master 3) ASUS DVD-ROM E616 - Sec. Slave Periodically following error messages were recorded by WinXP (only during startup): --- Event ID: 51 Source: Disk An error was detected on device \Device\Harddisk0\D during a paging operation. --- It's really weird since my XP doesn't use "D" partition for paging (and MS article 244780 clearly says that event can *only* be logged for paging I/O). Still I was paying little attention to these since everyting I needed worked fine. (Have no time to resolve bugs which are not actual bugs. :-) I'm a sysadmin, so it's kinda professional habit :-). But since yesterday I can't write CD anymore because of write errors. I've got the same trouble in Win2k SP4 which I also have installed, so I'm quite positive that it's a hardware error. While I experimented with writing, additional error messages were logged (as follows): --- Win2k AS: Event ID: 7 Source: Cdrom The device, \Device\CdRom0, has a bad block. Event ID: 9 Source: IdeChnDr The device, \Device\Ide\IdeDeviceP1T1L0, did not respond within the timeout period. Event ID: 11 Source: Cdrom The driver detected a controller error on \Device\CdRom0. ---- WinXP Pro: Event ID: 7 Source: Cdrom The device, \Device\CdRom0, has a bad block. Event ID: 9 Source: IdeChnDr The device, \Device\Ide\IdeDeviceP1T1L0, did not respond within the timeout period. Event ID: 51 Source: Cdrom An error was detected on device \Device\CdRom0 during a paging operation. --- Well... I found out that startup Event ID 51 (Disk) can be eliminated by disconnecting everything from Sec. IDE channel. Also I can write if I attach CD-RW as Pri. Slave but Event ID 51 (Cdrom) is still logged. It took me some 12 hours of testing to understand that I can't locate the exact source of the problems. :-(( It's hardware, and it's something on IDE, no doubt but what? CD-RW? IDE-controller? IDE-cables? Any help or suggestions would be welcome, especially if you ever encountered similar problems....