Installation: White Screen of Death

I just purchased a developer's licence for Gravity Forms. When I installed the plugin on my site (everdale.org), I clicked "activate plug-in" and got a white screen of death.
I then went into my cPanel, deleted gravity forms and got my dashboard working fine again. After reading your forums, I de-activated all of my plugins, re-installed gravity forms, and then activated only gravity forms. I received the white screen of death again, so I am inferring from this that the issue is not a conflict with one of my current plugins.

Do you have any other suggestions for what may be causing this issue and how I might deal with it?

I'd also like to note that prior to purchasing gravity forms I downloaded the requirements check plugin which worked just fine.

I really appreciate your help. Unfortunately, I tried both of your suggestions to no avail. As I'm trying to find a solution, I am starting to get outside of my abilities to problem solve this, so I contacted our website developer to help me. Here was her feedback:

"I have changed the theme a couple of times, once to one I did, and one to a wordpress standard. Both had the same reaction to the plugin. The second time even just having it in the plugin folder brought up the white screen.

It was installed through FTP and activated through the plugin panel. I had a look at the error log on the site and this is what I saw that I think is an issue.I am not sure what it means as this is getting into hard MySQL and PHP programming stuff."

Would you be able to shed any light on the error message below?

SELECT * FROM wp_4_calendar WHERE event_recur = 'Y' AND EXTRACT(YEAR FROM '2011-01-28') >= EXTRACT(YEAR FROM event_begin) AND event_repeats != 0 AND (EXTRACT(YEAR FROM '2011-01-28')-EXTRACT(YEAR FROM event_begin)) <= event_repeats
ORDER BY event_id made by require, require_once, include, get_footer, locate_template, load_template, require_once, dynamic_sidebar, call_user_func_array, widget_calendar_upcoming, upcoming_events, grab_events
[18-Jan-2011 18:37:13] WordPress database error Got error 28 from storage engine for query SELECT * FROM wp_4_calendar WHERE event_recur = 'M' AND EXTRACT(YEAR FROM '2011-01-28') >= EXTRACT(YEAR FROM event_begin) AND event_repeats = 0
UNION ALL
SELECT * FROM wp_4_calendar WHERE event_recur = 'M' AND EXTRACT(YEAR FROM '2011-01-28') >= EXTRACT(YEAR FROM event_begin) AND event_repeats != 0 AND (PERIOD_DIFF(EXTRACT(YEAR_MONTH FROM '2011-01-28'),EXTRACT(YEAR_MONTH FROM event_begin))) <= event_repeats
ORDER BY event_id made by require, require_once, include, get_footer, locate_template, load_template, require_once, dynamic_sidebar, call_user_func_array, widget_calendar_upcoming, upcoming_events, grab_events
[18-Jan-2011 18:37:13] WordPress database error Got error 28 from storage engine for query SELECT * FROM wp_4_calendar WHERE event_recur = 'U' AND EXTRACT(YEAR FROM '2011-01-28') >= EXTRACT(YEAR FROM event_begin) AND event_repeats = 0
UNION ALL
SELECT * FROM wp_4_calendar WHERE event_recur = 'U' AND EXTRACT(YEAR FROM '2011-01-28') >= EXTRACT(YEAR FROM event_begin) AND event_repeats != 0 AND (PERIOD_DIFF(EXTRACT(YEAR_MONTH FROM '2011-01-28'),EXTRACT(YEAR_MONTH FROM event_begin))) <= event_repeats
ORDER BY event_id made by require, require_once, include, get_footer, locate_template, load_template, require_once, dynamic_sidebar, call_user_func_array, widget_calendar_upcoming, upcoming_events, grab_events
[18-Jan-2011 18:37:13] WordPress database error Got error 28 from storage engine for query SELECT * FROM wp_4_calendar WHERE event_recur = 'W' AND '2011-01-28' >= event_begin AND event_repeats = 0
UNION ALL

Thanks again for your help.