Unable to format my laptop

Hi,

This is Monica here.....Iam briefing my problem that am facing with my lappy here....Recently I bought a datacard and the installation & activation was successfull.I was having Kaspersky AV installed on my laptop,I thought of trying Symantec Endpoint Protection,so uninstalled Kaspersky.....I was connected to the net that time...but the minute I uninstalled Kaspersky the connection was lost & the system hanged.So I hard booted the system and installed SEP,but this time the system got hanged with a stop error screen.Since then everytime I connect my data card,its giving Found New Hardware Wizard and the status on the dialer always shows modem unplugged......even when the modem is connected.So the ISP tech uninstalled the dialer and tried ti reinstall it but failed.The previous installation is still in the system.So they upgraded the Service pack,drivers...even then there is no use....So finally told me to format my laptop.Even that is not happening.....I tried with 3 different CD's still the same result.....Now my laptop is not having any AV program in it....Meanwhile I also ran the latest MSRT and Taterf Worm was detected & cleaned successfully.....Still my dialer is not getting installed.....If someone could help me out on this...pls provide a soln ASAP......The OS is xp.......And laptop is of Compaq's.

Regards,
Monica