I've been having a hard time getting very far in the game before having to restart. I have been using a variety of MODS so I can't really pin point which one is causing the problem.

Does anyone know if any of the MODS from the skyrimnexus is causing problems especially with the latest update 1.8?

There are so many mods on the Nexus I think it'd be pretty much impossible to do a survey like you're asking. The best way to get help for your specific situation would be to tell us what quests you've found are bugged and how, and most importantly, what mods you're using and your load order.

Also this would probably be better served in the Skyrim Mods section since the question is about...well...mods.

To be quite frank I am not even sure its the MODS. Its just that the Dark Brotherhood quests seem to be bugged.

Ive never had issue with the dark brotherhood quests. But yeah, Mods can bug games easily. Especially any mod that is from before the current patch and has not updated.

You already have a very similar topic in the appropriate forum. http://www.gamesas.com/topic/1421286-why-are-most-of-the-dark-brotherhood-quests-bugged/