Windows System file is moved to virus vault. Help!

I have my computer formatted yesterday and Windows XP (service pack 3) is installed. I have installed “Vista Inspirat” (kinda Vista theme for XP) to get looks of Vista.
Today, I installed AVG 8.5.409 and scanned whole computer. It removed four windows files to virus vault. These files are:
1. C:\WINDOWS\system32\scrnrdr.exe;“Trojan horse Agent.AXNF”;“Moved to Virus Vault”
2. C:\WINDOWS\system32\uodnady.dll;“Virus identified Win32/Cryptor”;“Moved to Virus Vault”
3. C:\WINDOWS\system32\uodnady.dll;“Virus identified Win32/Cryptor”;“Moved to Virus Vault”
4. C:\WINDOWS\system32\winlogon.exe (544);“Virus identified Win32/Cryptor”;“Reboot is required to finish the action”
(I have copied this by exporting scan results overview to a .csv file)
When windows starts, I get an error message saying that “C:\WINDOWS\system32\scrnrdr.exe” file is missing; and this pops up two times. It also said try searching this file. I tried searching it in all computer, with hidden files included in search, but nothing showed up.
There’s no problem so far. Are these files needed? I’m afraid I have to re-format my computer to restore these back, as there’s no option in AVG to restore these files back from the virus vault.

Any suggestions are appreciated.