Had lots of trouble with Dell hardware - but excellent support in most cases.
(I think 25% of our Dell motherboards broke in the spring of 2006 because of a batch of bad capacitors, and I think I heard rumours that more broke after I left that place, but service was always great until recently, and I'm now so far away from hardware I don't know if it is Dells fault or the sysadmins fault in a recent case I think of.)
The capacitor plague. Pretty much everybody in the industry was hit by that to at least some extent:
> "Major vendors of motherboards such as Abit,[9] IBM,[1] Dell,[10] Apple, HP, and Intel[11] were affected by capacitors with faulty electrolytes. In 2005, Dell spent some US$420 million replacing motherboards outright and on the logistics of determining whether a system was in need of replacement.[12][13] Many other equipment manufacturers unknowingly assembled and sold boards with faulty capacitors, and as a result the effect of the capacitor plague could be seen in all kinds of devices worldwide. "