DNA "refusing" to be run in agarose gel

[Ketil Thorstensen]

Honored contributors to the molbio.methds-reagnts!

I have a peculiar problem with persuading some of my DNA samples to run in 
agarose gels.

When loading DNA samples on agarose gels I have on several occasions observed 
a strange (to me) phenomenon: after application of a sample into a well a 
streak of the sample may follow the pipette tip upon withdrawal. When the 
sample in this way comes in contact with the buffer surface, the sample very 
rapidly spreads out to cover the entire surface. During this process most of 
the sample in the well is "sucked" out.
There is no recognizable pattern as to what sample this may happen with. It 
is, however, frustrating when precious samples are lost (the last one was a 
1.9 kb DNA probe)  :í-(
Could anyone enlighten me as to what I am observing, and how to prevent 
this from happening again?

Thank you very much,

Ketil Thorstensen, Ph.D.
Dept. Clinical Chemistry
University Hospital
Trondheim, Norway