These type of errors usualy occur when something happend with the server. There are so many codes that mysql could show, so there is no way they could be puplished here...
If you have shell access to your server, or to any other server that has MySQL installed, you can execute the following command:
perror XXwhere
XX is the error code.
Here is a list of most common error codes. Also on that site, you have more chances find explanation of your error
[UPDATE]
For Windows systems, the perror.exe you can find in 'mysql\bin' and you can execute it from command prompt (aka DOS prompt)
