Dell /inspiron 1545 laptop
Windows not shutdown properly very often

My laptop is inspiron 1545. i bought it at chennai spencer plaza.very often my pc is not shutdown properly.this information appearing on window when i am booting.initially i thought some os files were missing.now i formatted my os still that problem persists. though i had 4gb ram and 250gb HDD my system is hanging many times.i dont no what is the problem is, i am having warranty too.so please tell me what the problem is and give the solution for this problem.