Its the same experience for me and a couple of other players I know. I seem to recall Polarite reporting it over on QuakeOne.com quite some time ago but it never seemed to get fixed. ProQuake used to be supported by Baker but sadly he's been rarely seen on the forums and so forth
(Baker, if you are reading this come back old friend
)
If it helps, Qrack still records without any issues (for me at least), and Darkplaces also works. You might also try EngineX or DirectQ which work well on lower power PCs (like mine)
Kr's
Monty