WebPlus X7: X7 has messed up my Navigation Bars ?

I have a single web site. Originally designed in X4. Recently upgraded to Web Plus X6 without any problems at all.

Was then tempted into moving to X7 but am now unable to do anything on account of constant error message !!

Have tried going back to X6, but the problem has also transferred to the older version too!!!

The message I am getting is a box indicating that "Navigation bar failed to generate a Preview".

In design view the bar shows in usual place at top of pages, but with no buttons / menu showing.

The box also asks if I want to disable previews and I have tried ticking both options "Yes" and "No".

But continue to get the error box which pops up every five seconds.

Have visited Tools / Options / View, and ticked the box to enable "Preview JS Navigation Bars". But this has no effect either, and the "Navigation Bar failed to generate Preview" continues to pop up at five second intervals.

Any ideas please, as I am now unable to make any updates to my site - and am very much regretting the latest update

If it helps my site is www.risepark.plus.com but was last updated before the problems arose. SM:HELP