It's not a bug.
Quick save is used for when you wanna possibly quick load the game from a certain point while it is already in progress. Like you died doing something stupid or made a bad quest choice and wanna quick load from the last quick save.
Regular plain ole' save is just that. When you restart the game tomorrow, your save game will be loaded.
Peacemaker is right about loading the quick save from the load menu.
Just do a usual save when you quit the game and you'll have no problems when you go back to play later.
Well its indeed a bug in the new ver 1.03. Quicksave works like what you mentioned on older version I had, ver 1.0, but having some slight glitches now. Eg, let say i get to sentinel island through the portal in maxos temple. I killed a dragon elf and immediately quick save on on the moment of his death. When I press my quick load hotkey, its a miracle I found myself inside maxos temple, where my screen display exp I get from killing the dragon elf. And when I get back to the location where the dragon elf is, its indeed dead and nothing there anymore and I do receive exp from it.
It can be solved by pressing the manual load hotkey, press esc to close it and use the quickload hotkey again, then it will load properly again if you only to quickload numerous of times, eg. at the merchants. If I didnt utilize the normal load menu or load the quick save file through normal load menu, I will be forever started off in maxos temple every time I press the quick load key. Although its not a serious bug which prevent you to progress in the game, but it can sometime be very annoying.
Another thing is the need to resummon the necromantic creature every time morph out of dragon form. In older version 1.0, the creature will always stays, but not in the 1.03 anymore. I not sure its a bug or its meant to be so though.