I don't pretend to know about hardware issues so wild guesses suggest that, if it passes POST, and if, once the system is up and running there are no other issues like halting, shutting down, Blue Screens, and so on, the motherboard is OK and there are no blown or bulging capacitors. Google BAD CAPS for more on that.
I will let others discuss the hardware issues though.
So, tell us more about this setup. Any USB devices connected? Is the computer connected to any Home Network?
If there are any USB devices connected, disconnect them before booting up. If the computer is on a home network, eg other computers, or a wireless printer, make sure they are all on. I have seen recently here where a wireless printer with a recent driver update had slowed boot up to a crawl. Also, if this computer has any "Mapped drives" from others on a network, and that mapped drive is inaccessible, that might be a cause of the slow boot.
If you had not said that this also happens with a different drive with a cloned OS, I would have mentioned the DMA/PIO Switch Flip. http://winhlp.com/node/10
Although the article is about CD/DVD drives, it also happens to hard drives and although the system reports it is in DMA Mode, often a 'flip' from DMA to PIO then back again will solve slow performing hard drives.
But like I said, this doesn't seem to be the case here since the same problem happens on your other drive. But I wonder. Since this is an OS setting, could the setting have been exported when you cloned the drive?
These are all bad guesses, so lets also see what others here say.
Whenever I boot my computer (Dell Dimension 8300, 8 years old, with Windows XP Professional, SP3), I get the Dell splash screen, indicating that the BIOS is loading, etc.
Then it turns into a black screen, with a cursor line blinking in the upper left corner. It does not even appear that Windows is trying or starting to load.
After about 5 minutes of this, Windows finally begins to load, loads in a reasonable amount of time, and then works perfectly normally and at normal speeds, until the next time it is re-booted.
I have had the motherboard tested, showing normal. I have replaced the hard drive with a new faster larger one, with no change (I did NOT reload Windows, just restored everything to my drive using an Image Restore).
It was working fine until a couple of months ago, then starting acting as described above.
I can live with the time to load Windows, etc., but am concerned that this could be a symptom of something about to fully die, and would rather know about it ahead of time, in case I have to make some repairs/replacements while I still can while it is still functional.
Any ideas of what could be causing this would be appreciated.