Strange mouse behavior w/ External Display

[rockstar7x]

Greeting people!   I have the following problem:

I use an old Dell Latitude D630 as my main computer, it features a Core2Duo processor 2.0ghz and 4Gb`s of Ram and it runs Windows 8.1, so, whe I plug it to my external 19" display, either in Extended mode or using the 19" display as Main, after a few minutesm my mouse starts lagging like crazy, my touchpad too!, but the Joystick (Little blue dot between G and H keys) works just fine, and it happens randomly after 5, 10 or 15 minutes, sometimes I hear the sound Windows plays when you disconnect a device,then my mouse and touchad fails. If I disconnect my external Display, everything goes back to normal.

This happens on XP, 7 and 8.1, I always use the correct and updated drivers.

Btw, this does not hapen when I use my 42" TV as external display.

Could it be my external display power brick not giving enough power? It makes a buzzing sound.