Just a quick one here, I've recently installed gingerbread to my HD2 using cyanogenmod 7, previous to this I was running froyo through a different mod. My problem is this, many of the market apps that ran fine on my phone before are now listed as incompatible and Google play refuses to let me download them. I know that they are compatible, because like I said, I ran them perfectly well on my froyo mod. Is there a way around this problem?
It's really hard to say without knowing specifically what previous ROM you were using, but there are two possibilities I can think of:
For screen/LCD density specifically there are a handful of apps that will help you modify it. Based on Chahk's comment, values of 160 and 240 may be good to try if it is set to something different than that.