If I click on File - Export, the program crashes.
What program are you talking about? What version NUMBER?
What operating system are you using? What version NUMBER?
Lightroom Cassic 11.5
First thing I would try is resetting the preference file. https://www.lightroomqueen.com/how-do-i-reset-lightrooms-preferences/
If that doesn't help, try turning off the Graphics Processor in LrC: Preferences->Performance->Use Graphics Processor set to OFF
Please post your System Information as Lightroom Classic (LrC) reports it. In LrC click on Help, then System Info, then Copy. Paste that information into a reply. Please present all information from first line down to and including Plug-in Info. Info after Plug-in info can be cut as that is just so much dead space to us non-Techs.