my pc is acting strange?

hi guys,im new to this page,and i,m a bit afraid on my situation.I,ve been having problems with my computer,the 1 sign is that the cd/dvd drive opens and closes by itself like when i open the cd/dvd drive it closes by itself,like someone or something is telling to do that,and it happens when i,m connected and when i,m offline to and the thing is that cmd won,t open,it show in task manager but i can,t see it,and the main thing is that i used to have this problem before,but i formatted my pc and now it comes again and i,m worried if somoene is having acces to control my pc and i,ve tried making an antivirus scan,and still no virus found,any suggestions or answers would help,thank you.

Did you follow these steps to Clean Reinstall - Factory OEM Windows 7 so you know you have the best install possible? If not I'd do it over deleting all partitions during the reinstall.

Be sure to read the Special Note to HP Owners at the end that will show you how to preserve the onboard Diagnostics triggered by the ESC key, if it will still run. Now would be a good time to try and run it.

Otherwise work through the Troubleshooting Steps for Windows 7

thank you for answering greggrocker.Well at first i had reinstall windows all again(formatted) but i still had the believing that my pc wasn,t a 100% virus free,and now my pc has become worse.I,ve readed the article you posted and i,ll try it later.I have a question.1 Lets say if you reinstall windows again wouldn,t all virus go? 2 could a virus last a formatted pc? and thank you again for replying

If you correctly deleted all partitions before install, yes, unless the virus is traveling on your network. Run Malwarebytes full scan on all PC's, make sure your router firewall is turned on.

To be extra sure wipe the HD first with Diskpart Clean Command.

Use the latest official installer for your licensed version, burned to disk or stick with tool provided in Clean Reinstall - Factory OEM Wi ndows 7

is it possible that the virus could infect an usb internet modem?,because i,m begining to think that it is with the modem,cause now my pc read my usb modem as a dvd/cd drive,and if scanned with malwarebytes but no virus found,and it beggining to change some windows program making them corrupt or acces denied, and another question if my usb internet modem was infected how could i disinfect it?

and i didn,t have any partitions,i,ve just formatted the whole pc

Where did you get Win7?

I gave you specific steps to try so report back the results of each.

well i used windows 7 ultimate cd from microsoft and i,m not a computer savy and i read the post about how to "Clean" or "Clean All" a Disk with the Diskpart Command does this format the current hardrive connected to my pc or what does it do?? and i currentlly have a strange thing that show my usb modem internet as cd/dvd drive,is there a way that i can show you via a snapshot?

Yes you only need the Clean command and it will wipe the drive to prepare it best for reinstall. Be sure to back up any files.

You can take a snapshot and upload the file using the paper clip icon in reply box, or use the Snipping Tool in Start Menu to snap it. Screenshots and Files - Upload and Post in Seven Forums - Windows 7 Forums

my dvd,cd drive had taken the cd drive name,everytime i put my modem it,s take that place and cd/dvd drive icon dissapears