SynerGIS UserManagement Admin Web has to run in a 32 Bit Application Pool. If your DefaultAppPool has set the option "Enable 32-Bit Application" to "False" (see figure below) SynerGIS UserManagement Admin Web will have troubles with certain database drivers.

Application Pool 64 Bit in IIS7
To avoid these troubles create a new Application Pool (see figure below) and change the Application Pool of the UserManagement Admin application to 32 Bit Application Pool ("Enable 32-Bit Application" to "True").
Important note: Do not change the default application pool to 32 bit, if other applications run on a "64-bit default application pool". For this purpose please create explicitly a new "32-bit application pool" and use this pool for UserManagament Admin.

Create new Application Pool in IIS
If working with Internet Information Services (IIS) 7.5 be sure that the Application Pool Identity of the Application Pool, your UserManagement Admin Web Application runs in, is set to "Network Service".

Application Pool Identity in IIS
Note: Be sure, that the attribute '.NET Framework Version' is set to 'v2.0'.