Unable to Login SQL server management studio:sql server 2005

Hello All,

I am unbale to login SQL server management studio with below scanario:

Server Type:Database Engine

Server Name:XXX

Authntication:Windows Auth

After enter "Connect : button below eeror is displaying

Error:"Canot connetc to XXX server

Additional information:

Attempted to read or write protected memory .This is an often an indication that the other memory is corrupt(System.Data)

Note:Database is connecting R3trans return code 0000

SAP is working fine

Please provide suggestion and inpuits its very urgent

Thanks

Nekkalapu