I'm running Lubuntu 18.04 64-bit and I'm using both PCManFM and Thunar as my main file managers, and I'm experiencing some issues with Thunar.

Whenever I'm transferring a file with a invalid filename to a USB FAT32 formatted, I get a message similar to this:

But after this message appears, my mouse freezes. The entire system seems okay and responsive, all but the mouse.