Plugin Limit

Is there a limit to the number of plugins one can have? Or a max memory allocation to plugins?

I installed additional tags plugin and got a fatal error: out of memory…. Removed it and it went away. Tried another plugin from WP repository and it also gave a fatal error: out of memory on install. They give errors in different php files at different lines.

I do have a load and have many in mu from this site, plus quite a few for BuddyPress.

If there is a memory problem is it something that can be changed in WP, or is it something I need to change with my host or can I do it through CPanel?

Can any one advise? Thanks