Problem in intial boot up

Hello,

i had just changed my power supply unit to a higher power rating one. i have connected all the connectors properly, but since i have done that the computer whenever it is started after being stopped is not able to boot up properly. it gives the error " a disk read error occured , press ctrl alt delete to restart"., whenever i do that it will still not boot up. but if i go to the BIOS setup and then save and exit it boots properly. once it has booted if u restart from windows it will reboot successfully and everything runs like normal but if u shutdown and then start the computer back it will again give the same error and wont boot up. this problem has started since i changed the power supply unit. iam not sure ifthe problem is with that as it works fine after the boot up is successful.

can anyone please help me out with the above problem.