It's rare, but sometimes the mouse cursor freezes even when it's not a cold start. And the cursor may still remain frozen upon restarting, although, again, this has been rare for me. The worst that I ever had happen, I think, was the cursor remaining frozen after 3 consecutive restarts or so. (Happened, like, once in an entire year of using the mini.)
Normally, I don't have to restart at all. And if I do, the problem usually goes away after the first restart. To make the experience even smoother, like many here, I assigned a restart script to one of the keyboard's function buttons. So even when it freezes, it's just a tiny inconvenience.
On another note, has anyone been able to get File Sharing to be on? On my mini under OS 9, it's stuck on "starting up", even after waiting for 1 entire hour (note: TCP/IP enabled). Not sure if it's an issue with my OS 9 configuration, or a Mac mini OS 9 issue.