Yellow screen when starting up Mac

Not something I've seen with a MacBook Pro; I'd expect to see only a gray screen with an Apple logo during a boot, possibly with the progress (spinner) indicator.

I'll assume you've tried rebooting and that's not clearing this, so I'd try the following:

• Does the same yellow display still occur after peforming a Safe Mode boot and then rebooting normally? (Safe Mode flushes various caches, so rebooting through that sometimes clears boot-time weirdnesses.)
• I'd also try resetting the system management controller. (That does sometimes clear some boot-time video display weirdnesses.)
• If that fails and if your MacBook Pro is covered by AppleCare, I'd ask Apple Support about this.

I had that same problem - the brief flash of a yellow screen at start-up - with a previous version of 10.9.x. I've seen a number of people reporting the same phenomena lately. I think that it's just a graphics glitch that is occurring on some machines and will only be remedied with an update.

I wouldn't worry about it...

Clinton

Some of the display settings are stored in PRAM.

Reset PRAM: http://support.apple.com/kb/PH14222

Best.