Check your boot order in the bios, make sure it is booting off the drive that has your windows installation.
When you power on your system repeatedly hit F8, if it brings up a menu with options like safe mode choose "repair my computer". This will load up tools for fixing issues with windows 7. Select startup repair, windows will go through common causes of windows not starting and repair them if possible.
If your computer will not give you this menu (it probably wont, given the error you are getting) then you will need a windows 7 or windows 7 repair CD to access these same tools. You do not need a CD that came with the computer, any windows 7 CD will work as long as its the same version (32 or 64 bit) as the version you have installed. Get a windows 7 cd from a friend or download one from the internet.
Put the CD/DVD into the computer then boot off the cd (you may have to change your boot order in the bios to boot off the cd rather than your hard drive). Once the CD is booted up, choose your language then click next, then choose repair options (or something similar). You will then be at the same menu as mentioned above, select startup repair.
The above process will repair most minor startup problems, however you maybe getting this message because your hard drive is damaged/failing. If startup repair is not able to get you up and running then I'd download seatools for DOS, this software is for testing your hard drive. You can download it from http://www.seagate.com/ww/v/index.jsp?locale=en-US&name=seatooldreg&vgnextoid=480bd20cacdec010VgnVCM100000dd04090aRCRD
Burn that iso to a CD and boot off it, again you may need to change your boot order in the bios. Once booted into seatools you want to choose to do a short test on the hard drive, this will take 3-5 minutes and will determine if the drive is mechanically sound.