The background isdark and uneven, suggesting that protein was in the running buffer itself. Most likely the apparatus was jarred and much of the samples was slopped out of the wells. The spilled sample would not resolve into bands, since it continuously entered the gel from the upper buffer compartment. That would suggest that the wells were too shallow, and some material spilled into adjacent wells. This symptom also shows up in perfectly good gels when the electrodes are hooked up backwards for a few minutes.
Protein migrates out of the wells instead of into the stacking gel.
Catching the problem within a few minutes salvages some of the information, but the pH effect that causes efficient stacking is compromised, sample is lost, and protein contaminates the running buffer. Judging from the lack of other symptoms, it appears that the gel was simply poorly stained. Coomassie blue dye staining solution can become contaminated with SDS if it is recycled. The dye becomes less effective and proteins don't show up as well as with fresh dye. As long as the proteins were precipitated in the gel by the acidified alcohol in the stain solution, the problem could be corrected simply by re-staining with fresh dye.