Replacing usbser.sys should not be that hard. Yes I have done it on XP with Arduino issues and on win 7 a long time ago.
My problems were related to the Adafruit version.
I always have "driver enforecement" OFF for Arduino drivers.
Are you a USER of that machine or an FULL ADMINISTRATOR ?
Did you run SFC from a command prompt after a safe boot to command prompt as that is the best way ?
If it were me I would first uninstall Arduino related items and do a major clean up before starting again.
Attaching some help info for that aspect.
Start by running SFC from the start up command prompt by using F8
Let it do its thing.
Re-boot when its done.
Do the major clean up.
Optional but often worth doing is a full security sweep using online tools and a few others (ask me if you need the steps)
Reboot when you are done.
Search "enable hidden administrator account" and enable
Then from a fresh copy of the IDE (you did not mention which version) I would start the install with driver enforcement OFF and any additional security such as antivirus OFF running it as a FULL administrator.
It may look like there is a lot to do there but I like to start from a known baseline.
CLEAN UP BEFORE INSTALLING ANOTHER COPY OF THE IDE OR ARDUINO CREATE.pdf (345 KB)