4.9.11 isn't the latest version of LimeWire. You can grab 4.9.21 (or maybe something newer ) from LimeWire.com's beta testing program.

A lot of improvements were added between 4.8 and 4.9. Under the hood, the downloading code was greatly streamlined (using Java's NIO package) to reduce processor usage and increase download speed. The changes caused problems on some people's systems. Later releases have ironed these out.

The message you got was probably when you tried going back to an older version of LimeWire, warning you that you can't use an OLDER version of LimeWire to continue downloads once the NEWER version of LimeWire has been run.