sometimes this is a problem with the tv that gets progressively worse. I now have to wait an hour and a half before my tv starts up when I turn it on. At first I thought it was a lamp which I replaced but did not fix the problem.
If you go to the sonystyle website and click on support, type in your model number and under "important news" (or something like that), you will find out that some of the KDF E50A10's have a systemic problem that require a free update. You then type in your serial number into the website and they will tell you immediately if you need the update or not.
If you do, you can schedule a service call through the website. I should mention that I have had horrible luck with Sony's support, granted I do live in a rural area but after the repair guy no-showed for our service call, it's taken me 4 phone calls and three emails to get to the point where they are calling me back. Strange, we are a sony family but potentially no more!
One other thing that Sony recommends (in case your tv does not need the upgrade), is to make sure the tv is plugged directly to an outlet and not through an extension cord.