Here are two videos that go over the fundamentals of license troubleshooting. Whenever I WebEx to a customer’s computer, I go through the steps shown in these vidoes. In almost all cases, this is enough for me to resolve the problems.
Troubleshooting 101: The License Server
Troubleshooting 101: Softimage cannot find the license server:
Note – this second video was done for 7.5. For 2010, ADSKFLEX_LICENSE_FILE should point to your license server, not to Autodesk.lic.