Nvcpl.dll is a DLL (dynamic link library) file, created and used by NVIDIA Corporation for the correct use of display properties of their graphics cards. It is installed along with graphics card drivers when installing a NVIDIA graphics card.
The file nvcpl.dll is a legitimate file that comes with NVIDIA graphics cards, and should not be confused with nvcpl.exe which is a worm virus. You may see nvcpl.dll running in system processes, especially if you have display properties open on your computer. You should not delete the file, as it forms part of your display drivers, and could cause system instability should it be removed.
It's not common to see error messages with nvcpl.dll unless the file is in some way damaged or corrupt. The most likely cause of nvcpl.dll error messages are if the user has accidently deleted the file, or an anti-virus program has incorrectly quarantined the file. Some of the messages you may see are as follows:
You can usually see these WinOS error messages when trying to change display properties, as the file is usually accessed when the display properties screen is invoked. Depending on the model of your NVIDIA graphics card, you may also see this on WinOS start up or shut down. In these cases, the fault is probably down to an incorrect registry entry.
By far the most common reason for these errors to appear is due to the nvcpl.dll file being deleted, either by the user or by an anti-virus program. Because the file is similar in name to a well known virus, nvcpl.exe, anti-virus programs commonly quarantine the file by mistake. In the first instance you should check your anti-virus program and recover the file from quarantine. Otherwise, try one of the following solutions: