Wiring issue related to ceiling fan and UPS Battery Backup

I am not an electrician - just a homeowner who is fairly competent with electrical work but knows when to call someone. I believe this is one of those times. I'm looking to get some thoughts on what to look for before I have someone come out on a wild goose chase. My house was built in the early 1970's.

I have an APC battery backup that I have my desktop tower plugged into. I have the USB lead from the batter backup going into the PC so that the PC can monitor the battery back and such. On a previous occasion, the battery backup started alarming and the code indicated a building wiring fault. I had my electrician come out and he basically just traced the line back to a light fixture in the attic that apparently had a loose connection. Everything has been working fine since then.

So, a few months ago, I moved my PC to another wall in the same room and when the volume is turned on for the PC, when I flip the fan light switch (I have lights and fan separated) I can hear the ding noise indicating that a USB device has been unplugged. I decided to watch the device manager and I can see the battery backup device disappear then immediately reappear. This sam behavior occurs when pulling the chain on the fan to change speeds. It makes the nose each time the chain is pulled or the switch is flipped, regardless of the state/speed of the fan.

I've checked the outlet the PC UPS is plugged into and it isn't tied into the switch - like for a lamp outlet, which I do have 1 of in the room.

So, that's pretty much the whole deal. Any thoughts on what may be going on? Any help would be appreciated.