Very strange, but there again the XP burning software, in my mind, has never proved itself to be 100% satisfactory and when you mix it with other third party burning software it can be even less reliable. I certainly find that its reporting of Disk space (used and free) is more of a guess than any accurate reading.
Bad blocks on a CD could cause Explorer to malfunction and report an error, they can cause Explorer to close and refresh itself, they also are prone to cause a total hang/freeze of a machine and require a manual reboot.
The above is more usual when you are creating CD's in different writers, and swapping them between different writers with different writing or reading speeds.
Not only do you have to take into consideration the speed of the writers, but also the speed rating of various brands of CD and DVD.
Another thing to watch out for is the Recording tab in the Properties for the CD/DVD drives. You can only have one drive at a time checked to allow burning (or erasing) with XP's burning software.
I have no real solutions for you only plenty of sympathy.