puppy 5.01 won't boot the second time from USB
I am quite new to linux. I made a live USB using Unetbootin and was able to run puppy linux 5.01 successfully for the first time. However, after rebooting, it does not load anything at all (neither puppy nor windows vista). All I observe is activity light of my laptop (Acer Aspire 5735Z) a couple of times. But then it turns off. I tried pressing F2 in order to load BIOS. But nothing occurs.
Please help! Thanks in advance.