After seeing prohibitory sign Snow Leopard it is obvious that you apparently want to resolve it. There are some cases reported in which there is startup issue with Mac Snow Leopard and prohibitory sign is such a trouble. In this type of situation while startup the system screen turns into Apple logo which is gray in color and after that prohibitory sign Snow Leopard appears. It means that your system recognizes the bootable Mac OS X installation but either due to software or hardware conflicts or OS X installation critical component missing. In such moment you certainly lose the access of system. So by someway or the other prohibitory sign Snow Leopard should be resolved as quick as possible. Resolving hard disk permissions through disk utility would help in overcoming this problem. Besides running the fsck command in safe mode is another option to dispel the issue. But still there is emergence of prohibitory sign Snow Leopard then reinstalling OS X is the mere option left. After the re-installation there is data deletion happens which can even cause file losing scenario. Here Mac Data Recovery Software comes for recovering formatted, deleted or inaccessible Mac data. It has proficient and remarkable recovery methods through which the recovery becomes quite simple and effective.