Windows 7: using dell inspiron 1520, after shut down and reboot bootloop prob

using windows 7 professional original, but the prob is, i open d laptop now. after login to windows, shut down laptop and reboot the laptop, it will stop at d loading starting windows hanging there. tried two different hdd for it. both same prob. suspected not hdd prob. it can be open after maybe it getting cold down, but even if u open booting for 1 min closing shutting it down, and reboot it again, it will not boot into windows. any idea on it? what possibility the faulty part.

even if i trying now, booting installation windows from cd, it will also stop later at loading microsoft corporation there. but once sussceeful booting windows, i can continously using without flaws. so what is the prob? trying two hdd also same...

1) At boot press F12 & run the Dell diagnostic tool.

2) Check your ram.
Memory Diagnostics Tool
Memtest86+ - Advanced Memory Diagnostic Tool

trying d dell diagnostic tools and no error found. and now using memtest86+ so far still no error found too.

tried and no error. but still prob arise

Work through these other troubleshooting steps