This can happen if you have the "Launch ProDOC when logging in" option turned on in your Preferences (click the Preferences button or use F5 while on the CU*BASE Home page), if the workstation you are using does not actually have ProDOC installed.  ProDOC is installed locally, but your CU*BASE GOLD preferences are attached to your CU*BASE employee ID, which means they are used no matter which device you are using to log in.  Usually that's a good thing, but if you happen to use a workstation not set up for ProDOC, the system will still try to connect and after trying for a while (can take several minutes) it will finally give up and give you the error.

Remember that if you access the Preferences window and uncheck the Launch ProDOC... flag you must actually press Enter or click the right-arrow button to save your changes.  

IMPORTANT NOTE:  The "Launch ProDOC when logging in" feature is not supported for clients with in-house imaging systems who are not on CU*Answers Imaging Solutions Release Management. Clients are required to have Smart Links enabled to use this feature.  Contact for assistance.