I had a similar transport glitch with 4.5.1 audio dropout, but no graphics issues: Songs that would play normally under 4.5 started to skip in the first few bars. It made it impossible to work with, so I downgraded back to 4.5 (May 21st version) to get everything working again.
Also noticed that the plugin scanner under 4.5.1 was ridiculously slow, usual scan time is around 8-10 seconds for 600+ plugins, but this took just under 2 minutes, every time I opened the application. I think the update needs a little more time in the oven!
[Specs: Windows 7 64 bit Home Premium SP1, 16Gb Memory Intel i5-4600K]