We've heard reports from customers that ink they are creating on their Tablet PC in OneNote 2010 sometimes moves or shifts unexpectedly. We know how frustrating this can be and are trying to release a public update to address this issue as quickly (and safely) as possible. To that end, we believe we have a fix and we are looking for beta testers before the public release.
If you are interested, please contact us via this blog (email or comments w/your email address) and we'll follow up with you once the build is ready. Thank you so much for your help with this and for your patience.
Update: We are no longer in need of people, thank you very much to everyone who offered to help, much appreciated!