strange glitch - any tool reverts to the PAINT tool when I move the cursor on the Stage view

hi everybody, I started seeing a weird glitch in SB Pro 6.

When I select any tool, say the cutter, the cursor changes to the correct tool cursor - but as soon as I move the cursor on the stage area to cut a drawing, the cursor (and the tool) REVERTS TO THE PAINT TOOL , preventing me to cut. The cursor shows a crosshair with a small P, like in the Paint tool, and it behaves like the Paint tool. (i.e. it is not only a cursor appearance issue, but the tool itself reverts to the Paint tool, although I have not selected it).

Has anyone seen this issue before? It’s quite annoying, and I have to quit the program and reopen it to get rid of it. I am looking for a fix or at least a viable workaround.

Thanks in advance.