[R] nonlinear curve fit of an implicit function

Hello, I want to perform a nonlinear curve fit in order to obtain parameter estimates from experimentally determined data (y in dependence of x), but with an implicit function, thus, a function of which I cannot isolate y on the left-hand side of the equation. As far as I understand, the function

[R] Rgui.exe cannot be set as default program under Vista wtih R2.10.1

Dear moderators, when I installed the latest version of R (R2.10.1) under Microsoft Vista (service pack 2), I ran into problems associating Rgui.exe with .RData files. On doubleckicking such files in explorer, they open in a Rterm window. Trying to associate Rgui.exe with the Rdata files via co