Weird problem with trying to change a variable

Lists?  Do you mean vectors?  Columns of dataframes are not supposed to be 
lists.

Ah. I've been using commands like

x <- list(c(1,2,3),c(2,1),c(6,6,1))
y <- c("A","B","C")
data.frame(I(x),y)

x y
1 1, 2, 3 A
2    2, 1 B
3 6, 6, 1 C

This sort of object behaves pretty much as I'd expect it to (using R 1.8.0
for Windows), though I've only made limited use. The x column has mode
list but class AsIs. Is this a legitimate use? 

(The documentation tells me that as.data.frame is a generic method, with
many implementations, including one for AsIs; and that the function I will
accept any object. I haven't looked into the implementation.)

Damon.