One of the very common problem I found in magento sharing hosting is product Image display. I spent hours on fixing this problem finally got very easy solution and it worked me perfectly.
I increased just memory_limit variable in php.ini file. In initial it was just 64M (which I did not care) but when I make it 256M(please be careful letter case for “M” because in some hosting it has problem). The problem is solved quickly.
if your hosting don’t have option to change php.ini file then rename php.ini.sample file to php.ini and place in ~/public_html/ path. this might work but I am not sure because it works for my hosting.
Enjoy and please let me know if you have other difficult.