I had the same trubble
Open trend and go to setting then find the "exception list" then Programs/folders then add
the tekkit folder
Win 7 EG. "C:Users(AddYourUserNameHere)AppDataRoaming.technicmodpackstekkitbin"
this should make every thing in the tekkit folder and sub folder, this well tell trend not to stop any thing in this folders
But be warned if any malicious files (eg, spyware, virus, etc) are in there they all so be allowed to run too
Enjoy and have fun tekkit a way