There is a new issue with Microsoft Outlook that is affecting files that are dragged and dropped from the emails. The effect on the files is causing null or bad 'Date created', 'Date modified', or 'Date accessed'. This is being worked on by SOLIDWORKS development under the following bug reports:
SPR#1182650 - "Crash mouse (hover) over SOLIDWORKS file with bad 'Date Modified', 'Date Created' or 'Date Accessed' value"
SPR#1182057 - "Crash selecting STEP, X_T, SAT file in File > Open Dialog due to Time Stamp (CreationTime, LastWriteTime, or LastAccessTime) of file."
The issue is crashing of SOLIDWORKS when mousing over a SOLIDWORKS file or selecting a non-SOLIDWORKS file. This can be determined with entries in the swxJRNL.swj which can be gathered with a SOLIDWORKS Rx Problem Capture. You can also find the swxJRNL.swj file here on the system %AppData%\SOLIDWORKS\SOLIDWORKS 2020\
This problem most likely happens after installing the Microsoft® Outlook® update KB4484343.
Currently SOLIDWORKS is working with Microsoft to fix the issue caused by KB4484343.
As a temporary workaround, copy and paste the file into the same folder. The Windows copy handler assigns new dates to bad files.