problem with an old .RData file

Dear useRs,

Today I've encountered a weird unexpected behaviour. It is not a real
problem for me and I can workaround it. But I'm very curious of what
could have caused it. 

Starting an R session in a directory with an old .RData my first command
was

library(MASS)

and i got

Errore in .Call("R_lazyLoadDBfetch", key, file, compressed, hook,
PACKAGE = "base") : C symbol name "R_lazyLoadDBfetch" not in DLL for
package "base"

In this session the same error appear when I try a save.image() or
simply answer "yes" when closing R (I can close only answering
"no"). But I manage to view and work with the saved environment.

The problem is strictly connected with *this* .RData file and
other .RData files saved in the same period with the same version of R
(2.1.1) work correctly. 

Now, the question. I'd like to look inside this file to search for
differences with working ones, but from within R I cannot save an ascii
version of this file due to this problem, and i do not know what kind
of compression was applied (gunzip says ?not in gzip format?).

Is there a way of inspecting this file?
thank you all for reading till now...

Marco Barb?ra

- Undergraduate student in Statistics 
  at the University of Palermo (Italy)

- Only free (as in freedom) software user

- Emacs lover