I have an external 120GB WD disc in a USB2 enclosure. The device keeps connecting and disconnecting occasionally and I get a "Windows - Delayed write failed" error. This happened on 3 PCs, with VIA and nForce chipsets on Windows XP. Same happened also when using a Seagate HD (both brand new). I also replaced the USB2 enclosure (tried both 3.5 and 5.25), USB cable, etc.
I also tried all the tips recommended on this very thorough discussion thread: http://forums.viaarena.com/messageview.cfm?catid=16&threadid=50469
I upgraded the BIOS and the system is configured correctly to page memory for programs (I also tried the "System Cache" option).
The same thing also happened on one PC when writing to a USB2 disk on key and also in the middle of a USB2 DVD-R burn.
I did not try it on other OS but heard this also happens with FireWire external drives.
It seems to be a MS bug but there is no MS documentation