It could be since I upgraded to Windows 1607 (yesterday) but I can't be sure as I haven't used X1 since before Christmas

I was getting it on 8.3.3. 64 bit (I think that's what I had installed) so I installed the latest beta ==> X1 Search 8.5 Beta Release 5 Build 6001os again the 64 bit version. But I'm still getting it.
I allowed it to send an error report with my email addy.
BTW : does X1 have about box that shows the version number ?
Phil D