Continuous beeping sound when booting XPS 1530

Here's the problem I am having. Whenever I boot my XPS, it will give me a continuous beeping sound for 15 seconds. The sound will come up right after the loading bar was full. And also, it takes a while for the loading bar to reach the end. But after that beeping sound, the windows will just boot straight up to the log in screen like nothing has happened. The laptop has never been dropped or anything. Thank you for your help.
I am using windows Vista Home premium and the laptop is 4-month old. Here's my laptop's spec:
-- XPS M1530 - Intel® Core2 Duo Processor T8300 (2.4GHz/800Mhz FSB, 3MB Cache), Genuine Windows Vista® Home Premium Edition
-- 2GB Shared Dual Channel DDR2 SDRAM at 667MHz (2 Dimms)
-- 256MB NVIDIA® GeForce® 8600M GT
-- Size: 160GB 5400rpm SATA Hard Drive
-- Sound Card-- High Definition Audio 2.0
-- Intel Next-Gen Wireless-N Mini-card

 

Check for memory faults mate using MemTest+ or Vista memtester

more info about beeps

http://www.pchell.com/hardware/beepcodes.shtml

 

Run diagnostics on the memory, To run the PSA diagnostics, perform the following steps: Shutdown the computer. Press and hold the <Fn> key, then press and release the power button. Release the <Fn> key when the lock lights above the keyboard begin to flash or "Diagnostic boot selected" is displayed in the upper right corner of the screen.