You should contact tech support with this issue. But here is something to check...
As a user of EG 3, did you define a library in the EG administrator to redirect your default output location to EGTASK? If so, you might try using the SAS Enterprise Guide Explorer (off of the Tools menu) to delete and redefine that library.
Another test you can do first: try changing the settings for Tools->Options->Tasks: Output Library to put WORK at the top of the list instead of EGTASK, and then try creating a query. If it works, then try the above step of deleting/redefining EGTASK.
The same thing happened to me. I have not reset my EGTASK yet for fear of losing stuff. If I unassign the EGTASK folder; rename the old EGTASK folder; create another EGTASK folder; copy everything over to the new folder; and assign the new EGTASK folder as a SAS library do all of my old projects still work?