Leroy.. here is a set of instructions.. you can try them all, or one at a time.. you may not like it, but it will cover just about everything with exception of a system reinstall...
First, go to Add/Remove Programs .. Delete SFC Op
Delete SFC OP game folder
Run Scan Disk
Run Defrag
Remove your ISP software using same method as removing OP
Scan disk and defrag again
reinstall your ISP software and get back online
Go to your ISP web site and check your DNS and Secondary DNS address (Dial up connection settings)
to check these find your Internet Explorer Icon, right click and select properties, click on the connections tab (if you don't see connections tab, then open Internet Explorer, go to your menu bar and click on Tools, then click on Internet Options,then click on Connections tab)
select your ISP in the white window then click on settings, then at the bottom near your name, click on Properties, then click on networking Tab, then click on Internet Protocol (TCP/IP) in the dropdown menu, then click properties.. you will see at the bottom of the box "Use the following DNS Server Addresses" .. depending on your ISP, it may or may not be checked, but most usually are and have DNS numbers listed...
double check your DNS and Secondary DNS addresses as compared to what your ISP states it sould be.. make sure that they match...
once they match, click OK, and OK all the way back to the Internet Explorer Connections tab box...
click settings again, and make sure "Automatically Detect Settings" is checked...
click OK all the way out,.. restart your system, then reconnect to the net.
If you have Ad-Aware 6, run it now, remove everything that it finds (make sure you use the update feature before running it, and all the settings are enabled for deep scanning and archive scanning is enabled)
If you have a Registry Cleaner, use it now to remove any invalid entries that may be in yor system registry.
Double check your system device drivers.. also check you mother board drivers (yes those get updates too.. if using Intel CPU, go to Intel.com.. AMD do the smae.. AMD web site) and also check your modem driver and system Bios for Flash Bios Updates...
Once you have done all this, reinstall SFC OP, Patch with 2552, and try game online... GSA..
If you still get Firewall Error of being dropped in game, then contact your ISP and see which ports that they may be blocking.. post them back here and many will tell you if they are needed for GSA online play...
Hopefully this will get you back online and in games soon...
Again, it is a pain in the Arse, but it is the best way to make your system clean and up to date and to make sure your settings are correct..