Internet Explorer issues

I've been trying to solve this IE registry keys issues on my own but my efforts were utterly hopeless.

I finally got rid of the malware residing in the system with the help from one of the people here. And I thought everything was now okay until my sister pointed out two things:

1. She can't log-in to Friendster
2. Even when she log-off from Yahoo and clicked "REturn to Yahoo mail", instead of the Log-in it is her mailbox being displayed.

What I had been doing were:

1. regsvr32 urlmon.dll on the Run command and click OK then did the same with

• Shdocvw.dll
• Actxprxy.dll
• Oleaut32.dll
• Mshtml.dll
• Browseui.dll
• Shell32.dll

Then restart the PC but that didn't work. So I check the registry keys and values and there were there so I no longer now what to do. Reinstalling the IE is far from my mind as IE is included in the OS and I don't have any Windows XP installation cds as XP is already pre-installed when my sister bought this PC. So can anybody help me?

Do this to repair IE: Try this 1st:
*From the Start menu, select Run.
*In the Open field, type sfc /scannow (Note: There is a space between sfc and /scannow)
*Select the OK button.
*Follow the prompts throughout the System File Checker process.
*Reboot the computer when System File Checker completes.

This is your 2nd option:
*From the Start menu, select Search, select All Files and Folders.
*Select More Advanced Options and place a checkmark beside Search Hidden Files and Folders option.
*Ensure that Search System Folders and Search Subfolders are also checked.
*In the All or Part of the File Name box, type ie.inf
*In the Look In drop-down menu, select C: or the letter of the hard drive that contains the Windows folder.
*Click the Search button.
*In the search results pane, find the ie.inf file located in Windows\Inf folder.
*Right click the ie.inf file and click Install on the context menu.
*Reboot the computer when the file copy process is complete.

Hey thanks but those two methods you mentioned needed a Windows XP cd and I don't have any. Like I said, this is a factory-installed Windows and when this PC is bought, no cd or System recovery disk was included. >.<