• Goto Start - Run type cmd.
• Type the following commands each after one -
• regsvr32 Msxml3.dll /s
• regsvr32 Dssenh.dll /s
• regsvr32 Gpkcsp.dll /s
• regsvr32 Slbcsp.dll /s
• regsvr32 Sccbase.dll /s
• regsvr32 Softpub.dll /s
• regsvr32 Wintrust.dll /s
• regsvr32 Initpki.dll /s
• regsvr32 Rsaenh.dll /s
• regsvr32 Mssip32.dll /s
• regsvr32 Cryptdlg.dll /s

If still Error 8004888D occurs in MSN Messenger then you can try one more solution.

To Solve Error 8004888D OF MSN Messenger -

• Go to Start - Run.
• Type "gpedit.msc".
• When the pop up window occurs you need to go to "Computer Configuration".
• in computer confuguration go to Windows Settings then Security Settings after that go to Software Restriction Policies.
• With this you can see "Trusted Publishers".
• Now check the Allow the following users to select trusted publishers.

try One of the tricks and i hope you can solve Error 8004888D From your MSN messenger.