We used to have this problem daily when we installed CS4. All files are stored on a network including our profiles as we can log onto any machine.
After a while it slowly stopped happening, however after recently installing CS5 the problem has come back with a vengeance (randomly 2 or 3 times a day). Its not the network loosing connection and it does not happen in any other program other than indesign. I use the full adobe master suite plus others like ms office.
Did anyone ever figure out the root of this?