standard SD card library does not work while "tinyFAT" does.

Hi, I'm having a rather strange problem with the SD card library. I'm trying to run the SD dumpFile example, and it outputs "Initializing SD card...Card failed, or not present" in the Serial monitor. after some hardware checking, I tried a different library, and this worked fine. However, I want to access folders and have multiple files open, create directories etc.

info:
Arduino Mega 2560

Hardware SPI (#define MEGA_SOFT_SPI is 0)
File present in root
file can be read by the tinyFAT library
Arduino IDE 1.0.1 (outdated, I know, but I have limited internet. I'll try on the latest version ASAP)
wiring done trough shield, so I can't use software SPI pins (and even if I put them on the hardware pins, it would still be slower)
the "Card failed, or not present" appears nearly instantly after the first message, a different response to what happens when the card is removed (waits a few seconds displaying the error)

I'll see if I can find anything else to try in the meantime, though I can't think of much right now.

What SD card? It might be a very slow or something.

Could it be something to do with how the SD card is formatted?

PeterH:
Could it be something to do with how the SD card is formatted?

The card is FAT/FAT16, so that shouldn't be the problem.
I don't know the make, but it's a microSD card in an adapter, and it's 2GB big. I'll try another card.