Opencart v2.3.0.2 Website Freezes When Logging In As Certain Customers

This is a strange one for me, hopefully someone can help.

Today we had a customer call us to let us know that the could not log into their account on our Opencart v.2.3.0.2 based website. The customer stated that when they tried, their mouse pointer just continues spinning until it eventually timed out and the customer was redirected to an Error 500 message.

As a test, I tried changing the customers password and logging in to the front end, and I got the same thing. Spinning Icon for about 4 -5 minutes then Error 500 message. In addition, I could no longer reach the site from my computer at all. It was like the site was down, but only from my computer. I could reach other sites, just not our domain. While this was happening, I tried reaching our site from my Ipad, and it worked no problem. I had to completely shutdown and restart my computer to access the site again.

Little additional info, after the restart I tried logging in using my own credentials and had no problem. It's just this particular customers account it appears.

Anyone have any ideas on what may be happening?

A little extra testing. I did a restart, and I still cannot access the site using Chrome, which was the original browser that I attempted to login as the customer with. I am however able to reach the site using Firefox and MS Edge browsers. I tried a Ctrl-Shift_Del and a few F5's in Chrome but still no joy.

Sounds like it could be mod_security or similar - contact your host.