IT dept causing havoc?? Never!
I feel your pain. I just hope you are going to recycle those 20,000 draft invoices...

Seriously though, you know what to do. Log a call and have IT come and fix the mess their upgrade created. Sometimes tweaks are needed when implementing an upgrade/new system.
Take a walk, get some fresh air and chillax Mrs.....you are allowed to vent, but it's not your fault.