To everybody,
After two weeks of struggle I finally managed to eradicate Prosearching from my PC. I will explain you how to get rid of it.

You have surely noticed that even if your Antivirus got rid of the trojan (Norton Antivirus Professional 2004 told me that the exe responsible is SAVENOW.EXE), your start page remains Prosearching/blahblah…

BUT I have located another exe that causes your start page to change. I have found it by exclusion. The name of the exe is OBJAIM.EXE (its icon represents a money pouch). If you don’t believe me, try by yourselves and see your task manager: you will find it there among your processes.

You could not consider OBJAIM.EXE as a threat because if you right-click on it calling its properties, you will notice that the date of creation is different from the date in which you have been infected.

If you should have any doubts you can launch MSCONFIG, uncheck OBJAIM.EXE from the automatic execution and restart your computer. When you return on MSCONFIG pane you will notice that another OBJAIM instance has been created, and this IS checked.

My previous attempts of getting rid of Prosearching start page failed because I have tried to manually delete the registry keys created by this malware, but I had not noticed an important fact: the keys were respawn after one minute of two! The registry keys are:

HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
Search Page http//prosearching.com/searchbar.html
Start Page prosearching.com
Start Page http//prosearching.com/passthrough/index.html?http://

HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Search
SearchAssistant http//prosearching.com/searchbar.html

Do not bother deleting them 'cause, like I said, they are re-generated after a few minutes.

Looking at these keys I have realized is another thing. There are MULTIPLE start pages and the malware cycles between them while your pc is active. That’s why you see alternatively:

PROSEARCHING.COM
PROSEARCHING
PROSEARCHING/PASSTHROUGH/…/youroriginalstartpage.

That’s all I have discovered. I hope these information would be useful. One last thing: please forgive me for my english but I am Italian.