I have some old molds that am finished using for now but im wondering if i can store them in a place that might cause mold.
My basement has been known to not exactly be dry and im wondering if it is going to completely ruin the mold. Its really the only place I can keep them for now and I don't have any good containers to keep them dry.

so, is it safe?

You could probably seal them in plastic bags, and/or store together with desiccants or moisture absorbents.

Would filling the moulds with resin solve this problem? The mould would have nowhere to go. Also, you get a free cast in. It should extend the life of the mould as well.

Resin releases isocyanates into the rubber, causing it to break down faster. It's generally a good idea to demold as soon as possible for maximum mold life.
BUT, you're onto a good idea---- plaster can be used to help your molds keep their dimensional stability. Then, wrap them in an airtight plastic bag (could be a garbage bag, but I use ziplocs.)

Also, keep in mind that silicones have a library life (meaning how long you can reasonably store them without them being ruined.):

Ooomo - 1year
Moldmax - 5-7 years
smooth-sil - 30+ years

www.smooth-on.com has some great FAQs worth reading.
Here's the one on mold storage:
http://www.smooth-on.com/faq_display.ph ... d=37&cID=4

*goes to get resin out of molds.