We've seen this as well and we have a customer experiencing it.  If you find any definitive hardware or O/S relationship, please post up here.

It was seen in older versions where if you were reading an email (previewing) and down 25-30 lines in the email and then the refresh happened, the cursor went to the top of the message.  This was reported by a customer.  We have and still see the flashing in the latest version 2.4 but have not experienced the "jump" of the cursor position.  I suspect it is somehow related to the video driver as well.  Recall in the 'legacy product'  that certain Dell installed Windows O/S's had a strange video issue.  Once reinstalled, the problem went away.

The customer just sent an email stating that he can reproduce the issue on his system of the jump.  Will try to remember to report back.