We need a lot more information that you have given. What is your operating system? What is your anti-virus program? How do you know this is an "msn virus"?
Do the following: With ALL browsers, chat and email programs closed
Update and run a full scan with your anti-virus program. Allow it to clean or quarantine all items found.
Still leaving all unnecessary programs closed EXCEPT your browser, do the following:
Please download Malwarebytes' Anti-Malware (MBA-M) to your Desktop.

* DoubleClick mbam-setup.exe and follow the prompts to install MBA-M.
* Be sure a checkmark is placed next to Update Malwarebytes' Anti-Malware and Launch Malwarebytes' Anti-Malware, then click Finish.
* If an update is found, it will download and install the latest version.
* Once the program has loaded, select Perform full scan, then click Scan.
* When the scan is complete, click OK, then Show Results to view the results.
* Be sure that everything is checked, and click Remove Selected.
* When MBA-M finishes, Notepad will open with the log. Please save it where you can find it easily. The log can also be opened by going to Start > All Programs > Malwarebytes' Anti-Malware > Logs > log-date.txt.

REBOOT the computer
Again close all chat programs and email programs.

Please Run the ESET Online Scanner and attach the ScanLog with your post for assistance.

* You will need to use Internet Explorer to to complete this scan.
* You will need to temporarily Disable your current Anti-virus program.
* Be sure the option to Remove found threats is checked and the option to Scan unwanted applications is Checked.
* When you have completed that scan, a scanlog ought to have been created and located at C:\Program Files\EsetOnlineScanner\log.txt. Please post that log for us as directed below.

REBOOT the computer
Next right click on the desktop and choose create new folder. Rename that folder HJT.
Next download HiJackThis to this new folder.
Open the program and click on HiJackThis to run a System Scan. Save the log.
Next post back here with copy/pastes of the MBA-M log, the eSET log and the HJT log.