Electrophoresis problem: Frowning bands and smeary ladder - (Nov/12/2015 )

Hello Everyone,

Recently my DNA electrophoresis gels have started looking strange (see attached image). I find this very perplexing since I haven't modified my technique, and up until this point they've been working fine. Gels are currently prepared and run with 1x TAE Buffer, 1.5% agarose, and 1ul GelRed/90 ml 1x TAE Buffer (added right before pouring). Gels are run at 100 volts for 30 minutes at room temperature.

So far I have tried: new ladder, prepared fresh buffer (using two different sources of millipore water), and run the gels in a different box.  

Can anyone thing of anything else I can try to resolve this issue? 

Thank you,

Tiffany

are you using the same batch of agarose? the same lot?

did you allow the gel to cool long enough?

are all of the solutions the same or are some newer than those used with the good gel?

to me, it looks like the agarose had not completely solidified.