The add-ons forum is literally a minefield, sprinkled with a few cookies in-between. What you really have to do is copy your saves folder to your desktop temporarily (its in base/saves) and then delete your Blockland Folder.
Now reinstall v8, copy your saves in. NOW pop on over to the Add-Ons forum and check out some of the add-ons, but only download the ones which look professional (because chances are they were made by someone who knows what they're doing) and not only that, but check the comments people have posted about it. Obviously if people are replying with "holy crap this totally deleted my folder and raped me simultaneously" then I strongly urge you to just not download it, because chances are its just another piece of crap that some 10 year old kiddy made because they want to feel appreciated in the big wide world of the internets. I can suggest to you now some of the mods I know that are perfectly fine and will not break anything (assuming you know how to install AND use them correctly):
- Anything i've made.
- Anything Kaje has made.
- Anything Trader has made.
- Anything TheGeek has made.
- Anything Badspot has made.
- Anything Pload has made.
- Anything Zor has made.
- Anything Randy has made.
- Anything Nitramtj has made.
Feel free to disagree with me, but you can't change my mind. I have tried almost all the mods submitted by the people listed above and I have found them to be very effective, they have yet to break anything, and they are very well done. Now the fun bit: these mods represent some 10% of the contents of the add-ons forum. As for the rest of the stuff in there, I wouldn't even touch with a bargepole, let alone download. I have tested a load of the other crap in a separate Blockland folder and i cannot describe how many things were broken and how many console errors were getting thrown at me per second. Reputation of the poster is an incredibly important factor to consider when you download an add-on, because people only gain reputations if they are notably good at something (or notably crap, but they are two such extreme ends of the spectrum that you should be able to tell the difference). To help put this into more visual terms, think of the other 90% of the add-ons forum as a vast array of STDs such as gonhorreah or clamidia. Once you get them inside your folder, they just don't want to leave. So the moral of the story is to protect your Blockland Folder like you'd protect your genetalia. Don't download the crap, just download the good stuff. That way your game will run a lot smoother, you can guarantee a more fun-filled experience for your users, and you won't get pusillanimous individual discharge coming out of various orifices.
Lesson learned? I hope so.