This error message comes from the application having to perform an operation and at that instant in time is unable to. This error is also generic and could be caused by a number of reasons, such as a slow computer or network, invalid rights, a software error, anti-virus software slowing the system or holding a file, and many other possibilities.

The fact that it happens every so often likely means that the problem is not being caused by a program issue, unless you can make the error happen 100% of the time following a particular set of steps - and if so, then please let us know these steps.

What function are you doing when you receive the error?