I can, quite considerably rule out your system specs as the cause. I'm sure there are users with 128 MB RAM and a 600 MHz processor that can scale textures.

For the fun of it, try this, to rule out the hollowed cube:

1. Create a standard block, not hollowed or anything. Pick a size, it shouldn't matter.
2. Assign a texture to this new block, pick one.
3. Try scaling the texture on this block to see if it works or not.

If it works in this case, you may have found a bug. Did you save your level as something other than untitled? This has been known to cause problems.