PLEASE ADVISE: Major Slowdown while Burning

I am running a Windows XP, athlon 950, 512 Mb RAM with a Plexwriter
40/12/40A

It was fine for a long time, I was able to burn discs in the background with
zero effect on the rest of the system.

A while back, suddenly, it started hogging processing cycles while accessing
the CD ROM, both when reading and writing. The CPU usage jumps to 100% and
the whole system more or less grinds to a standstill until the burn etc is
finished.

I believe it is driver/software related. Could anyone direct me to the
correct driver update to solve the problem?

Thanks

Joel