CRT Samsung monitor problem

[lunZy1]

So i have an crt monitor that i use as my secondary monitor and after i have it on for like 10 to 15 minutes it gets very noticeably blurry, but when i first turn it on it is really clear, i can not seem to find people with this sort of problem on google and so i came here, do you guys have any solutions? thank you if you can help me out.

 

[lunZy1]

I have solved the problem, if you have this problem, go to "Screen Resolution" "Advanced settings" "Monitor" "Screen refresh rate" and change it to 60 Hertz or anything lower than 85 Hertz, for some reason it made my screen blurry when it was set to 85, after setting it to 75hertz my screen became very clear and this problem explained above no longer there. i'm using an SAMSUNG SyncMaster 753df.