problem after update arc s

[mhmdbasheer]

hello ..

I have updated my xperia arc s to (LT18i_4.1.B.0.587)  by using Flashtool but after updating now I am facing a problem .. that I can't install applications .. I get error " application not installed " .
And there is other problem it is about storage.. I can't download any thing from internet if SD card  taken out the device although ther are 310 MB free space in internal memory .

sorry for my bad language ad I hope to find help

[Uliwooly]

where are you downloading apps from? 

[mhmdbasheer]

from other sources except Google market because it's unallowable  in my country ..
like 1mobile market ..
and I already tick on ‘Unknown sources’ option .

[Uliwooly]

well that's most likely the issue, the app might not be the correct version for your phone