I believe that sodium laureth sulfate--an ingredient in almost all liquid soaps and many shampoos--causes seizures in me. Has anyone else had this experience or heard of anyone who has?

I'm not sure if that is possible. According to the Epilepsy Foundation:

In about seven out of ten people with epilepsy, no cause can be found. Among the rest, the cause may be any one of a number of things that can make a difference in the way the brain works. Head injuries or lack of oxygen during birth may damage the delicate electrical system in the brain. Other causes include brain tumors, genetic conditions (such as tuberous sclerosis), lead poisoning, problems in development of the brain before birth, and infections like meningitis or encephalitis. About 30 percent of the 180,000 new epilepsy cases every year begin in childhood, particularly in early childhood and around the time of adolescence. Another period of relatively high incidence is in people over the age of 65.


As for the ingredient that you mentioned, here's some info I found on the subject:

From: http://www.keras.it/english/news.htm :

"First, let's look at Sodium Lauryl Sulfate (SLS) and Sodium Laureth Sulfate (SLES). These ingredients are use as sudsing agents as well as solvents. They work so well that the big industry uses them as engine degreasers, garage floor cleaners and car wash soaps. You'll find them in adult shampoo, toothpaste and even in baby shampoo.

In a study conducted by Keith Green, Ph.D., formerly of the Medical College of Georgia, SLS and SLES retards healing and keeps children's eyes from developing properly, can cause cataracts in adults, and delays in the healing of wounds in the surface of the cornea. They can build up in the heart, liver, lungs and brain and SLS is such a caustic cleaners that it actually corrodes the hair follicle and impairs its ability to grow hair. So the shampoo you use could actually be causing your hair to fall out!"

From: http://www.makingcosmetics.com/make_cosmetics_soaps/09_unsafe_ingredients_cosmetics.htm :

Sodium Laureth Sulfate and Ammonium Laureth Sulfate (SLES, ALES): The CIR Panel has recently stated that SLES and ALES produce eye and/or skin irritation in some human test subjects. The severity of the irritation appeared to increase directly with concentration. However, SLES and ALES have not evoked adverse responses in any other toxicologic testing. It was concluded that both surfactants are safe as presently used in cosmetic products.