Seeking HELP w/Virus Trojans and dll. probs

Hey guys, working on friends pc trying to clean it it, seems her teens have messed her up. Anyways; heres the deal
#1- window keeps popping up after login-C:\WINDOWS\system 32\xlibgfl254.dll
#2- window pops upC:WINDOWS\shell.exe
#3- back door trojan,agent,PTA gamadril 2007 1203
#4-virus found LOP hetp
#5-virus found Win 32/Poly crypt ptch
#6-Trojan TR/Dldr.ConHook.Gen
Running xp home, intel x 86 Family Model 4 2533 Mhz w service pack2 Build 2600
some off brand pc made especially for cheap sales thru AOL. Says it was a promotional sales deal... OK, now i uninstalled all her crap programs, and I installed AVG anti-virus, AVG antispy, Cleaner, Rogueremover, to stay on there, but non of them can get rid of the virus's or trojans, temporarily installed AD-Aware 2007 and a couple other leading free antivirus p[rograms but nothing can get rid of the above listed malwares and virus's...it seems at least one of the virus's has attached to something and keeps multiplying...can't get rid of it, am stumped,,,Please help, and am thanking you now...

 

update to this post, i was reading some other posts on here and found some other anti -spy removal programs , one of which told me about Vundofix V6.7.7; this cleared uproblem with the trojans and virus's. now the only probs left are the dll. and the exe, probs,,, if anyone can assist me with that i would greatly appreciate it, thanking again in advance