CD Rom not visible + no safe mode in Win7

Hi There,

i joined those two problems, beause it might be connected. Please advise. CD ROM is sometimes visible sometimes not. I tried already many solutions from different forums: change booting sequence to bring CD ROM first, remove battery and start up, AutoFix of Win, check cable connections, dell diagnostic tools, upper and lower keys.

So the sympthoms are following: when i start up comp and i can hear characteristic sound of lifting cd in the drive i know that CD ROM will be visible this time (in bios and win), booting goes quite fast, system start up as well. then i want to use it, i open cd or input new cd, cd is started to be read, and... that's it. CD ROM disapearing.... sometims is starting up without this characteristic sound, so i know no cd rom this time :(. When it was visibe couple times i tried to change firmware from A103 to A203, but no succesfull, it disapeared again during this proccess... what was strange nothing happend to flash memory, drive was behaving the same next times. What is really interesting, removing battery and starting up is helping to find CD ROM by bios, but later in Win it is disapear again. When there is no this sound even dell diagnostic tools don't find this device in computer.

The other problem is lack of safe mode. When i try to start it, computer is restarting itself. I tired with virus and malware scaning, registry fixing etc. no resultes. Sometimes during starting up safe mode i can reach login screen, i enter the password and system finds it as not correct, when i am 100% sure it is correct... and restarts right after that. sometimes i can even not reach login screen and system is restarting just after choose.

Computer specs:

Dell Studio 1745

Intel Core 2 Duo T6600 @ 2.2GHz

Win 7 64bit SP1

CD ROM - TSST TS-T633C 12.7mm Slotload 8x DVDRW       

Please help. I was really loyal Dell's user at home and in office, but i think i am changing my mind slowly...