Monitor is turning purple for a second and kind of blinking

Yeah compared to 7 years ago they are a bargain. I paid around $630 or $640 for my 17" Iiyama plus $50 for shipping, you couldn't get them in local stores and I had to haggle a little to get them to bring the price down to that amount to match a compebreastor. $50 off. :-) It's got a Trinitron type tube so maybe it is the monitor that's gone bad. It turned purple and stayed that way. I left it off for most of the day and when I turned it back on it was still purple, then it changed back to the way it's supposed to be. I think I'm going to wait until it goes bad again before I replace it so I can be sure the problem is with the monitor and not the graphics card. I think I'll bring the monitor to the store where I'm going to get a new one and ask them to hook it up to a computer.

Thank you.