update to version 17.3 did not occur when I chose to accept

Comodo Dragon informed me about v17.3 being ready. I chose to download and install this. Notification at top of the v17.2 browser showed a button, "Relaunch and Install", so I clicked this. The browser closed, my normal desktop was present,.... .... .... and nothing else happened. No installation. No installer displayed. The same comodo dragon browser v17.2 unchanged.

Several minutes later, I opened Comodo Dragon (still v 17.2), saw the same notification at top announcing that new version is available, so I chose it again. The same thing. Nothing happened after I clicked on Relaunch and Install.

(In any case, my version 17.2 still works excellently.)

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Comodo Dragon Browser currently at version 17.2
Windows XP, service pack 3.
Extensions present: CraigsPreviewer 1.0, Mailto 1.19.2, W.O.T. 1.2.11
(Any other information needed?)
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