One of my users had a weird problem that was fixed by going through a series of reset procedures. This is what the tech told us to do:
A) ArcMap soft reset
Step I: Rename Normal.mxt file as Normal_old.mxt
1. Go to the path for Normal.mxt (C:\User_profile\AppData\Roaming\ESRI\Desktop10.0\ArcMap\Templates)
2. Rename the Normal.mxt folder to Normal_old.mxt.
3. Launch ArcMap and check if the issue is resolved.
Step II: Rename the ESRI folder
1. Go to C:\User_profile\AppData\Local
2. Browse to the ESRI folder and rename it to ESRI_old.
3. Go to C:\User_profile\AppData\Roaming
4. Browse to the ESRI folder and rename it to ESRI_old.
5. Launch ArcMap and check if the issue is resolved.
B) Disable Background Processing
* In ArcMap, go to Geoprocessing > Geoprocessing Options
* Disable Background Processing and Click OK.
C) Disable Hardware Acceleration and While In Remote Desktop Session
* In ArcMap, go to Customize > ArcMap Options
* Go to Data View
* Disable While In Remote Desktop Session and click OK.
* Disable Background Processing and Click OK.
D) Clearing display cache
* In ArcMap, go to Customize > ArcMap Options
* Go to Display Cache
* Click Clear Cache and OK.
Relevant documentation:
*
https://community.esri.com/t5/esri-technical-support-blog/troubleshooting-slow-performance-in-arcgis...*
https://support.esri.com/en/technical-article/000008152