Blaming it on heat is bollox. If *any* pocketable device got hot enough to damage a glass or plastic screen then you could be sure you would have a hole in your leg well before the screen could get affected.

For me it started when I used the device extensively in hot environmental conditions, in the 40 to 52 °C range.

same here.

Please, don't speak on things you clearly have no clue on.... Overclocking does not put the CPU in a "perpetual high" state. This is not a PC from the 1990s, when overclocking meant the CPU ran at the highest frequency without rest. Overclocked N900s (and even PCs these days) spend lots of their time at lower levels, and only use top speed when doing real work. Most N900 spend lots of time at 0Mhz, the resting sleep state that they all enter when there's no activity. (You can see for yourself, by using this script on your own N900.) Again, overclocking could never cause this. If the CPU ever got hot enough to do this type of damage, it would have already fried itself and the much more heat sensitive LCD layer between it and the screen cover.

To the Op: If you're able, it may be worth removing the flaking cover skin (which has a high chance of breaking the touch screen, so be cautious) and putting a protector on it. It may be worth trying a wet-apply screen protector instead, like Skinomi, since it may mask some of the existing flake in the current cover. I put a Skinomi on mine after the first set of cheep stick-on protectors peeled off. It has a slightly different feel, but is quite nice, and has a rather interesting "self-healing" property. (Something to do with it being a polymer that reacts to oils from the skin... so says a chemist friend of mine.)

I'm using screen protectors from 1st day, and never ever experienced such issues. I can't imagine, why someone wouldn't use screen protector on such device.

BTW, this all "overclocking as the cause" discussion gave me a good laugh.

/Estel

The real cause is very likely to be both skin-oil from contact with fingers, and exposure to direct sunlight. Sun and oil together (along with high temperatures) can cause this type of thing quite easily. Also, other chemicals on one's fingers can do crazy things to plastic. I recall once having touched one of the covers for my N6230 with suntan lotion on my hands. The chemicals and sunlight together turned the clear plastic to a foggy milk-white, and the blue to a dark purple in a matter of a couple hours. That gave me pause about using said lotion the rest of that summer.

This happend with my friend after he used a bad screen protector and looks like there is something stock on his screen and cant be removed so he bought a good protector and the touch feeling is good but it is still a little hard for reading

It happened during the German winter. I wasn't even using the N900 much, as it's not my primary phone anymore. It just happened for no apparent reason.

Suggesting hot temperature likely has little or nothing to do with the deteriorating screen?

I have the same problem. How much doest it cost to replace the screen?

ps. today the vibration started to freak out. Maybe after 2.5 years N900 comes to na end...