Occasionally through some fault of your own or just the wonderful randomness of windows you may encounter an error whereby you get logged in with a temporary profile. You get a very nasty looking message saying
"Your user profile was not loaded correctly! You have been logged on with a temporary profile.
Changes you make to this profile will be lost when you log off. Please see the event log for details or contact your administrator."
Here is a solution path that may help you.
Log in with the local administrator account or domain admin account
*If you don't have a profile in the user folder skip to #4
If you have information in your profile that is lost you should browse to the profile directory and back it up. The profiles are typically stored in c:\users\... Copy the entire profile directory somewhere else on your hard drive outside of the user directory
Delete the profile folder from c:\users - Make sure you have your profile copied elsewhere before deleting this folder. For example c:\users\vince you would delete the vince folder. Do NOT delete the actual c:\users folder.
Open the registry, Start->search box type regedit
Accept any of the warnings and browse to the following folder and expand it HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList
You should see several folders with weird letters and number that mean nothing to you, just ignore that you don't know what they mean and click on each one until you find the offending profile. There is a listing under each of those folders called ProfileImagePath. This setting will give you the location of profile. It will be somewhat descriptive enough that you should be able to find the profile name you were trying to log in with.
When you have found it delete the entire profile folder that starts with the funny numbers and letters, by right clicking on it and click delete.
Now if all went well you should be able to reboot your machine and log in.
Once you have logged in you will need to copy anything you backed up, and you may need to log out and back in as administrator in order to access the backup you made.