Lets see if I can say this again and be clear. This whole issue is about a hack that has nothing to do with the software of classifieds. There is no inc_ads.php that is part of your classifieds 2.41 software.
Perhaps you forgot that you installed this hack.
http://www.photopost.com/forum/showthread.php?t=116508
Now if your new server does not allow you to run a getimagesize I dont know what to tell you honestly. If that is your path and
Warning: getimagesize(/classifieds/data/16/1malegrazpastel0045.JPG): failed to open stream: No such file or directory in /classifieds/inc_ads.php on line 119
You can try to get rid of errors surpress them like so
getimagesize
would become
@getimagesize
My suggestion is that if the server is incompatible with a hack your running then you need to remove the hack.