MDAC

Could someone tell me what MDAC is and what it does? I installed a Photo Program for a family member and during the install, the installer said that it was updateing MDAC. Now ever time that the computer is turned on, it is taking forever to loadup.I was asked to unstall the Photo Program and I did, but the computer is still booting up real slow. Is there any way to find this MDAC and unstall it and put the computer back like it was without reformatting the whole harddrive and restalling everything.