Regarding the "Verifying DMI Pool Data...Boot From ATAPI CD-ROM:Failure..." issue, while this can be caused by any number of things, I suspect that you are seeing this because the machine is set to boot from the CD-ROM and there is not a bootable disk in the drive. If you start the machine with the CD-ROM selected as the first boot device it will give you a boot failure for the device when boot instructions are not found there...it will then move on the the next boot device to look for the instructions. Changing the boot priority in the BIOS settings so that the System Drive (HDD) is the first boot device with the CD-ROM as second will usually stop this message.
The Task Manager may be a little tougher. First, let's take a look in the system32 folder to see if the executable is even there. With a machine of this age, who knows what may have been removed over the years.
Click on the Start button...then click on "Run". In the input field, type system32 and click "Ok". In the system32 folder that opens, look for the actual program (taskmgr.exe or taskmgr) to verify if it's even in the folder. If it's not there, copy the program from your other machine and transfer it to the current machine's system32 folder via flash drive or other removable media. Then try the Task Manager again by either pressing Ctrl+Alt+Delete or by right clicking on the task bar and selecting "Start Task Manager" from the menu.
If taskmgr.exe is present in the System32 folder, but will not open, we'll take a look at the associated registry entries to see if the problem is caused by an improper Data Value there.