Ok I gave it another chance as I didn’t have anything to lose really, and this time it’s turned out ok. I think what might’ve been doing it was that with my previous installation, there was an option to enable buddypress theming, forums and groups on all blogs, which I ticked and this time I didn’t.
I did as @mercime suggested, I installed the BP Template Pack. After I activated it and set it up I no longer had access to the network admin area! Luckily though I had my wp-config and .htaccess files up to date and backed up on my computer so I just ftp’d it into place overwriting the previous files. Now since I did that, I no longer have access to my dashboard at all! But at least I could now load the buddypress pages ok.
Thankfully, it’s only a brand new install so I haven’t really lost anything but I will have to re-install the whole network again and I won’t be using the template pack again.
And @aces, it’s because the template pack fixed the front-end loading issue that I can’t see how the memory limit would be preventing buddypress from loading.
