As Vincent said, we'd LOVE to have more information about this bug. It seems to happen only on some machines, so may have something to do with what other programs are running, and so forth. If you can experiment at all along those lines, or even try to keep track of what you did right before the problem arose, we'd really appreciate it.
Richard Will do - but do you know if this is a cross-platform issue or a windows-specific one? I haven't had any luck pinpointing the culprit (or how to replicate this), and it will be helpful to know if this is platform specific. -Joon