Inspiron 6000 - Reboot Loop Issue When Laptop Moves

This is my first post, so please forgive any rookie mistakes.  I have an Inspiron 6000 laptop that is giving me issues.  The laptop runs flawlessly when XP loads; however, it goes into a reboot loop after POST every time I take it anywhere.

After months of this, it eventually fried my hard drive.  CHKDSK /R got me further along but still did not allow a complete OS load.  At that time, I thought that the hard drive was the issue.  I bought a new drive, reinstalled Windows XP Pro with all drivers, and have been running well.  Yesterday, I took the laptop to a friends house and lo and behold...the problem returned.

The problem is as follows:  The BIOS posts seems to be okay and moves to the initial Windows XP screen with the blue progress bar beneath.  After a second or two, it reboots and the "Dell" screen reappears.  When it asks about Loading Windows normally, last known good configuration, etc. I have tried all options.  Selecting Normal or Last known config gives the same result.  It attempts windows and then reboots.  Safe mode does not load either.

I removed the hard drive, battery, memory, etc. to reseat everything.  Turning the laptop upside down and removing the battery seems to fix this issue.  I think this is coincidental, but I am lost at this point.  Before replacing the hard drive, the battery trick stopped working.  The system specs are as follows:

Dell Inspiron 6000
Win XP Pro SP3
2 GB RAM
Intel Pentium M, 1.73 GHz
Video:  915 GM/GMS, 910 GML Express Chipset Family
Western Digital WD1600 (160 GB EIDE)
Broadcom 440x 10/100 Ethernet
Intel Wireless 2200BG
NEC DVD+/-RW ND-6650A

My questions are as follows:

1)  Is there any track record of this motherboard showing connection issues with hardware?  For example, hard drive, battery, etc?

2)  Is it possible that the motherboard has any loose parts that are shifting in/out of place?

3)  Why does turning the laptop over and removing the battery fix this issue?

4)  Are there any diagnostics that can be done to troubleshoot this issue?

5)  Does anyone have a similar issue?  If so, what have you done to fix this problem?

Please note that this issue does not happen when the laptop is left on a desk for long periods of time.  While this is a "fix"...it defeats the point of having a laptop.

I appreciate any comments / suggestions / questions.  Please remember that this is a new WinXP Pro install with SP3.

Thanks,

Brooks