Windows 7: start no effect

very strange problem,

start or the windows orb, bottom left

click has no effect

ctl+esc opens ok

done the normal checks with Windows 7 pro, no new updates

no new programs installed

avast, malwarebyts, superantispyware, all come back clean

google the problem this machine is not the only one to suffer this

any chaps got a fix or know why, i thought about keyboard combination has

dissabled but ?

Welcome
Try a system file check

Type cmd in search, do not hit enter, right click and run as administrator

In the cmd prompt type sfc /scannow

If that does not work a system restore from before the problem may help.