Model 3000 K100 #57061334
Here's what I've experienced. If anyone has been advised of a suitable workaround, I'd love to hear it. This has been very frustrating and is absolutely an engineering snafu from Lenovo.
I had identical issues to OP. Quickly ran out of space on C: and had to go back and uninstall everything and re-install on D:. Then had to make new directories on D: for My Documents, My Videos, etc.
Even with that done, there are so many files that need to go on C: that 30G just isn't enough. (pagesys is 2.5G for instance)
Tech support has told me the following: (paraphrased)
1) If I can't remove anything else from c: the only way to fix the problem would be to use the restore to factory settings option (wiping out everything on C: (but not on D

and starting that partition fresh.)
This isn't an option atm because I have some small programs and utilities (such as VPN) installed that would be a pain to reconfigure.
2) Lenovo's One Key Recover requires the partitions to remain as when shipped to work correctly.
Any resizing of the partitions (especially C
will render One Key Recover (and the system restore) useless.
3) They do not support or recommend any partition software and
doing so voids your warantee.
So...I'm between a rock and a hard place.
My last phone call to Lenovo tech support was 30 minutes ago. I was hoping that if enough people made them aware of how much trouble this is, they might come up with a solution. (nope)
I'm going to do a little more research to see if any of these forums users have a better solution.
If not I'm am going to
- void my warantee
- make my c: drive bigger
- uninstall Lenovo One Key Recovery
- install another program to ensure my files are backed-up properly and
- never buy Lenovo again.