I am using an MRC-600 with a Panasonic optical disk drive, using WORM or Phase-change rewriteable disks, and generally collect data sets directly to this drive. Every so often during a write, I get a lock-up which is only cured by switching the OD drive off and back on. I also get occasional savage crosslinking of files which results in trashed data. The problem seems worst with WORMS. Any ideas of where to look for a solution to this problem? [log in to unmask] Smithkline Beecham UK