I running ACR 8.7.1 on Windows 7 Pro 64 bit.
Today when I went to use the Graduated Filter everything on the screen greyed out when I clicked on the image to mark the start point for the graduation. As ACR was at full screen it was impossible to exit since all buttons were greyed out.
Pressing Ctrl+Alt+Delete showed Bridge and an Error running in Task Manager. Ending the Error and returning to ACR showed all buttons/sliders back to normal but if I tried to use the Graduated Filter again the same problem occured. The only way to get back to normal seems to be quitting ACR and shutting down and restarting the computer. It doesn't happen everytime I use ACR but so far today this has happened about 4 times which is very annoying - it has never happened prior to today. I have not made any changes/updates to the computer.
Any suggestions as to what causes this and if there is a solution to prevent it happening would be much appreciated.
ACR currently has a problem when in full-screen that is it always on top of other windows, including error windows.
Unmaximize ACR and then try the brush operation and see if the error becomes visible.
Many thanks for your suggestion. I have opened and closed ACR several times to try and induce the problem but so far the problem hasn't re occured. I'll keep trying.