Flashing tooltips

[Forex Trader]

Can ayone help? I run 2 instances of MT4 and both today, have developed the same problems. Firstly, when clicking on the tabs to change to another worksheet, the charts do not always respond. It can take 3 or 4 clicks before the windown changes to the next chart. Secondly, all the tooltips will now not remain steady when the cursor is over the chart item, but flash on and off at about 2 flashes per second. This happens if I hover over a moving average or a worksheet tab, for example. Does anyone have any ideas as to what may have happened. I have rebooted the PC, but the problems still occur.

Many thanks