Actually, sometimes a complete disconnect of the power cable for 30 seconds, pushing the power button, and then plugging it back in, and turning on may initiate a refresh sequence in some computers. It may need to do with ACPI or a system management processor that may be installed, but if you're not sure, give it a whack.
As for the mouse not working, one shouldn't affect the other, but it may be an issue with the monitor displaying the cursor. You did install the monitor driver right?
Do you have specifics on the mouse and monitor, what version of Windows? optical, wireless, etc...