Jumping PDFs

Hello,

I have a problem with all of the Adobe software (reader X and professional) that I have been using lately in that the PDF, when in normal viewing mode, jumps up and down on the screen. The top tool bar, with the File, edit, view tabs continiously disappears and then reappears and this causes the shuddering effect. If I push a button on the keybord it stops but starts againas soon as I release it. The PDFs are stable when viewed in full screen mode. This problem does not happen with any of my other installed programmes only the adobe ones.

Has anybody an idea why this might be happening and a even better a fix. I have uninstalled and reinstalled all Adobe software twice now in an attempt to fix it.

Thanks