Buffer overflow on the mouse buffer. The i8042prt is the Win2000 and later driver of the PS/2 mouse/keyboard port. This event indicates that the buffer that stores mouse movements and clicks filled up before you stopped typing or moving the mouse (in simple words you entered data faster than the application could process it). From the moment the buffer fills up, all incoming data is lost (since the driver works on a First-Come-First-Served basis). This event is encountered usually when a program with high base priority stops responding and the system does not read data from the mouse port buffer for a small amount of time. If you move the mouse quickly during that time, you''ll fill up the buffer.
This event record indicates that the Buffer that stores mouse movements and clicks filled up before you stopped typing. It means you entered data faster than the application could process it. Some of the data was lost.
Wait until the application has processed the stored mouse input, and then enter more data. Be careful not to work ahead too far. If you get this message often, the buffer size should be increased by someone who is familiar with Regedit32 (Usually the person with administrative rights on your computer).