You should update IC2 to 1.97 and BC3 to 3.1.6.25+ to avoid further problems. Also, update to the latest forge version (3.4.9.171) in 1.2.5, as it fixed some bugs with other mods. 3.3.8.170 is a solid choice as well. You can find Buildcraft 3.1.6.25 here:
MCPC+ 1.2.5 Ports list
Scroll down to BuildCraft3 and click the Google Sites link in the 3.1.6 #25 r3 section. IC2 1.97 can be downloaded from here.
Alternatively, you could download the DNS Techpack for 1.2.5, which is available in the AT Launcher and that still has a working download link here. Tekkit 3.1.2 also works fine, but you'd have to content yourself with the much worse BC2.