could not install sisx file now

[azureskyi16]

hi all,
I come into a big problem today, I could no longer install the sisx file into my phone.
Details: My phone is N97, and I use Nokia PC suit to install software. I always choose Nokia Application Installer to install sisx files, however, suddenly it does not work anymore. It gives the error message "Nokia application Installer, operation failed"(even when I try to reinstall application which I have successfully installed before ). But I can still uninstall applications from my N97.
Another problem is that when I try to open the "E disk" using Nokia Phone Browser, I could not do it.
Any suggestions? Should I update phone software?

[wizard_hu_]

Is your device connected in PC Suite mode?

[azureskyi16]

yeah, I have installed sisx many times, and suddenly I get this problem.
Does this mean I get cell phone virus？ Is there any anti-virus software for cell phone?

[wizard_hu_]

If it is a virus, I would rather expect it to be on your PC. What happens if you copy the .sisx files to the memory card (in USB mass storage mode), and try to install them on the device (e.g. open them with the built-in File Manager)?

[azureskyi16]

hi, wizard_hu
thanks for your reminds, you are really everywhere.
When I use your method to install applications, it works. Now I really confused, it seems it's not the problem of my cell phone. I use the latest version of Nokia PC suite, it could not be the problem of software, then what??