range problem on code alarm

Anyone know what type of equipment would cause range issues on a remote start?  Heres the scenario.  Today i have put in three remote starts(2-Code ca420, 1-Code ca500).  On all three units i have had range of about 15 feet inside the store garage and about 3 feet outside.  I tried the usual swapping everything on the first one.  Finally i drove down the street to a K-mart Parking lot(less than 2/10ths of a mile away) and everything works great on all three. This happened to me once on friday Oct.19 for about four hours  and it has been doing it all day today.  Obviously something must be working on the same freq. band and causing interference, but I have no idea where to start looking.  Any suggestions would be great.

I do not know if it has anything to do with your specific problem, but if you follow this link. It lists a problem with some of their antenna's.Installer, IT support, and FFL. I need less hobbies.

thanks for the link, but I was aware of the tb for them.  However its only for the Prestige models.  Its something outside that is interfering.