It's been a little while, but I had this happen to me before. The only differences besides the hardware was that I had some of the tabs disappearing as well as other elements of the GUI. I will add that Maya does't require the desktop to be set to 24bit as far as I know.
The way I was able to fix my problem was that for some reason a few of the configs got dorked up somehow and would not let portions of the GUI be displayed properly, so I saved all the stuff that I wanted and removed all the configs for my account. When you fire it up the next time, it should recreate all the configs.
I also had to go to someone else who had Maya 5 installed and get all the default configs and copy them over the ones existing on my HDD. You may not need to take it that far, that issue was all my fualt.
Hopefully that helps.