176 The system has been tampered with - error message on IBM PC

[WeZona]

I have an old IBM 300PL 550mhz desktop with Windows XP pro installed. The problem is that it only boots to Windows every third boot. During the first boot,after the IBM logo, this message shows:

187 Administrator password and boot sequences have been cleared
176 The system has been tampered with
Turn power to your system OFF and ON
The system is now locked

and it doesn't proceed. The second time this message shows:

System security - keyboard is locked
176 The system has been tampered with
Turn power to your system OFF and ON
The system is now locked
System security - keyboard is unlocked

On the third try, the PC boots to Windows.

I've tried researching the error messages, but the only possible solution I have come across is replacing three of the caps near the CMOS battery on the motherboard.

Source

Any suggestions or previous experience with IBM PCs would be helpful.

 

[MetalDwarf]

check for a chasis intrusion setting in bios or manual or jumper, office type computer (IE: IBM) sometimes have a little photodiode on the motherboard that detects if it gets bright in the case, which could be a sign of someone opening the case to steal/tamper with parts