To reproduce you can use the demo http://demos.telerik.com/silverlight/#ScheduleView/Ical and then click Export. Open the created file and look for lines starting with DTSTART or DTEND. You will see something like this
DTSTART;TZID=W. Europe Standard Time:20160509T050000Z
DTEND;TZID=W. Europe Standard Time:20160509T060000Z
According to RFC5545 Section 3.3.5 https://tools.ietf.org/html/rfc5545#section-3.3.5
>> The "TZID" property parameter MUST NOT be applied to DATE-TIME
properties whose time values are specified in UTC.
Some programs (e.g. Outlook) ignore in this case the Z at the end of the timestamp and treat it as something else. After manually removing the TZID part everything is fine.
Please fix the exporter.